Battle of Chochiwon

The Battle of Chochiwon was an early engagement between United States and North Korean forces during the Korean War, taking place in the villages of Chonui and Chochiwon in western South Korea on July 10–12, 1950. After three days of intense fighting, the battle ended in a North Korean victory.

The United States Army's 21st Infantry Regiment, 24th Infantry Division was assigned to delay two advancing North Korean People's Army divisions following communist victories at Osan, Pyongtaek, and Chonan earlier in the month. The regiment deployed along roads and railroads between the two villages, attempting to slow the advance as much as possible.

Aided by air strikes, U.S. Army units were able to inflict substantial damage on the North Korean armor and other vehicles but were overwhelmed by North Korean infantry. The two understrength U.S. battalions fought in several engagements over the three days and suffered massive losses in personnel and equipment, but were able to delay the North Korean forces for several days, allowing the remainder of the 24th Infantry Division to set up blocking positions along the Kum River near the city of Taejon.

## Background

### Outbreak of war

On the night of June 25, 1950, 10 divisions of the North Korean People's Army launched a full-scale invasion of the nation's neighbor to the south, the Republic of Korea. Advancing with 89,000 men in six columns, the North Koreans caught the South Korean Army by surprise, resulting in a disastrous rout for the South Koreans who were disorganized, ill-equipped, and unprepared for war. Numerically superior, North Korean forces destroyed isolated resistance, pushing steadily down the peninsula against the South Koreans who could muster just 38,000 men to the front line to oppose them. The majority of the South Korean forces retreated in the face of the invasion; by June 28, the North Koreans had captured the capital Seoul and forced the government and its shattered forces to withdraw further southward.

Meanwhile, the United Nations Security Council voted to send assistance to the collapsing country, and United States President Harry S. Truman subsequently ordered ground troops into the nation. However, U.S. forces in the Far East had been steadily decreasing since the end of World War II, five years earlier. At the time, the closest force was the 24th Infantry Division of the Eighth United States Army, stationed in Japan under the command of William F. Dean. Tellingly, the division was under strength, and most of its equipment was antiquated due to reductions in military spending. Yet despite these deficiencies, the division was ordered into South Korea, tasked with taking the initial "shock" of the North Korean advances until the rest of the Eighth Army could arrive and establish a defense.

### Early engagements

The plan was to airlift one battalion of the 24th Infantry Division into South Korea via C-54 Skymaster transport aircraft and quickly block advancing North Korean forces while the remainder of the division was transported on ships. The 21st Infantry Regiment was identified as the most combat-ready of the 24th Infantry Division's three regiments, and the 21st Infantry's 1st Battalion was selected because its commander, Lieutenant Colonel Charles B. Smith, was the most experienced, having commanded a battalion at the Battle of Guadalcanal during World War II. On July 5, Task Force Smith engaged North Korean forces at the Battle of Osan, delaying over 5,000 North Korean infantry for seven hours before being routed and forced back.

During that time, the U.S. 34th Infantry Regiment set up a line between the villages of Pyongtaek and Ansong, 10 miles (16 km) south of Osan, to fight the next delaying action against the advancing North Korean forces. The 34th Infantry Regiment was similarly unprepared for a fight; in the ensuing action, most of the regiment withdrew to Chonan without engaging the enemy. The 1st Battalion, left alone against the North Koreans, resisted their advance in the brief and disastrous Battle of Pyongtaek. The 34th Infantry was unable to stop North Korean armor. After a 30-minute fight, the 34th mounted a disorganized retreat in which many soldiers abandoned equipment and retreated without resisting the North Korean forces. The Pyongtaek—Ansong line was unable to delay the North Korean force significantly or inflict heavy casualties on them.

The regiment subsequently retreated to Chonan, where, the next night, the 3rd Battalion was heavily engaged in another delaying action. The 34th Infantry lost its commander, Colonel Robert R. Martin, and two-thirds of its 3rd Battalion's strength. The exhausted 34th Infantry Regiment retreated to the Kum River, near the 24th Infantry Division's headquarters. The 24th Infantry Division would make one final delaying action before it would be forced to make its final stand around Taejon, the only major defensible city left before the Pusan Perimeter being established by the Eighth Army.

## Battle

Having pushed back U.S. forces at Osan, Pyongtaek, and Chonan, the North Korean 4th Infantry Division, supported by elements of the 105th Armored Division, continued its advance down the Osan—Chonan road, up to 12,000 men strong under division commander Lee Kwon Mu in two infantry regiments supported by dozens of tanks. Behind it, the North Korean 3rd Infantry Division had yet to engage the American forces.

### Airstrikes

By July 7, the 21st Infantry Regiment had been established at Chochiwon, one of two roads to the Kum River and Taejon. The regiment was ordered to keep the road through the region open so supplies and ammunition could flow through it to the 34th Infantry Regiment on the front lines. The Americans spent several days unloading supplies from locomotives in the village. After blowing up all bridges north of the town, 1st Battalion was established on the Chochiwon road at Chonui, 12 miles (19 km) south of Chonan. Supporting it were one battery of 155-mm howitzers from the 11th Field Artillery Battalion and A Company of the 78th Heavy Tank Battalion with M24 Chaffee light tanks, as well as B Company of the 3rd Engineer Combat Battalion which was assigned to construct roadblocks and prepare bridges for demolition.

Around mid-afternoon on July 9, observers with the 1st Battalion, 21st Infantry, spotted a column of 200 vehicles led by 11 North Korean T-34 tanks, subsequently calling for an airstrike. For the next few hours, the U.S. Air Force ravaged the North Korean column with repeated bombings and strafing, and by sunset, half of the vehicles were destroyed or burning, and a large portion of the infantry had also been killed. The next day, a similar airstrike by B-26 Invaders, F-80 and F-82 Twin Mustang aircraft of the Fifth Air Force took place around Pyongtaek, with 38 North Korean tanks, seven half-tracks and 117 other trucks destroyed, in addition to a large number of infantry. Much of the village of Chonui was left burning, although South Korean soldiers and civilians had already abandoned it. In addition, the airstrikes caused some of the largest losses of North Korean armor of the war and were a major blow against the T-34 tanks, which had been so successful during previous encounters.

### Fight at Chonui

Meanwhile, the 1st Battalion, 21st Infantry, back at Chonui remained understrength. Half of the force had constituted Task Force Smith at Osan. B and C Companies were thus still refitting at Chochiwon, leaving A and D Companies to hold the line with a handful of replacements to fill the extra positions. The battalion numbered around 500 men in total. The 1st Battalion emplaced on hills overlooking the south road of Chonui, northwest of Chochiwon, and prepared to meet and delay the advancing North Korean forces, while the 3rd Battalion emplaced behind it in reserve. Around 0555 on July 10, the Americans began to detect North Korean movement through the morning fog. Fifteen minutes after daybreak, a whistle blew, immediately followed by small arms fire on the American positions. American forces at first fired indiscriminately into the fog until the regimental commander, Richard W. Stephens, stopped them. At 0700, the 1st Battalion then came under heavy mortar fire, and A Company on the leftmost ridge was assailed with fire from higher ground by North Korean forces of the 4th Infantry Division. The American forces began using 4.2-inch mortars on the North Korean positions to prevent them from advancing directly on their positions. Around 0800, the fog began to lift, and the Americans spotted four T-34 tanks in the village and subsequently called for another airstrike.

North Korean forces, meanwhile, flanked the American positions under cover of fog. The Koreans passed around the Americans' right flank and attacked the mortar positions in the rear. T-34 tanks also joined in the fight and also passed around the American flanks while obscured by the fog. Around 0900, the North Korean forces in Chonui initiated a frontal assault on the 1st Battalion, 21st Infantry's positions. An observer with the unit called in artillery and pushed back the North Korean infantry inflicting heavy casualties on the assaulting force. By 1100, the North Korean infantry, supported by several T-34s, was pressing on A Company's position, which was undermanned. At 1125, the requested airstrike came in; American aircraft rocketed the T-34s to no effect while strafing the Korean forces attacking A Company. The aircraft were able to push back the attack for several minutes before running out of ammunition and being forced to leave. The North Korean troops immediately resumed their assault.

One of A Company's platoons, under the command of Lieutenant Ray Bixler, faced most of the pressure of the North Korean assault. Tank fire had destroyed the American wire communications to their artillery, which began to fall on their own positions, believing that they had been overrun with North Koreans before Stephens could call it off. In the meantime, at 1135, Bixler's platoon was surrounded and destroyed; most of the platoon's men were killed in their foxholes by the North Korean infantry. Following this, men on the right flank began deserting their positions regardless of Stephens' efforts to keep them there. Finally, at 1205, Stephens ordered his men to withdraw. American forces had great difficulty retreating through the wet rice paddies, and a disorganized retreat followed as they attempted to pull back. During the retreat, several U.S. aircraft returned and, mistaking the soldiers of the 1st Battalion, 21st Infantry for North Koreans, began to strafe them. The aircraft inflicted no casualties, but the battalion overall had suffered 20 percent casualties, with 33 killed and 35 wounded during the engagement, as well as 14 killed in the mortar company.

### American counterattack

As the 1st Battalion retreated, Stephens ordered the 3rd Battalion to counterattack the North Koreans on the ridge to regain the position. The American attack was aggressive, and the 3rd Battalion regained most of the ground, rescuing 10 Americans captured in the first attack in the process. During the attack, the 3rd Battalion uncovered evidence of North Korean war crimes; six men from the 1st Battalion's heavy mortar company were discovered executed, with their hands tied behind their backs. Several M24 Chaffee light tanks, newly arrived from Pusan, were brought in the 3rd Battalion's assault, the first use of U.S. armor in the war. The M24s disabled a T-34 while suffering two destroyed throughout the day. During this time, the North Korean 4th Division pressed southward, bypassing Chonui to the west. Following it was the North Korean 3rd Infantry Division, one day behind, granting the Americans time to rest and prepare new defenses. The 3rd Battalion held the position until just before 2400 when it withdrew to its previous position with most of the equipment that had been lost by the 1st Battalion earlier in the day. At that position, the men discovered North Korean forces occupying its old foxholes, and K Company engaged in a one-hour firefight to drive them off. Meanwhile, 1st Battalion withdrew south to new blocking positions 2 miles (3.2 km) outside of Chochiwon.

At 0630 on July 11, four T-34s advanced on the 3rd Battalion's position, passing through a minefield without suffering any casualties. Following the tanks, about 1,000 North Korean infantry of the North Korean 3rd Infantry Division conducted a double envelopment of the battalion, setting up roadblocks in its rear to prevent resupply and evacuation of wounded. Simultaneously, heavy mortar fire struck the battalion's command post, destroying its communications center and ammunition stocks and inflicting heavy casualties. American forward observers were unable to communicate with the artillery due to the lack of communications equipment. The attack by the North Koreans was well coordinated, and North Korean forces driven from the position in the night had likely been able to gather intelligence about the battalion's position. In the ensuing fight, American forces were overwhelmed again, fighting in desperate hand-to-hand combat.

North Korean machine guns continued to assault the American lines, and Americans who had expended their ammunition were forced to use their weapons as clubs. Of 667 men in the 3rd Battalion, over 60 percent became casualties, including the battalion commander, Lieutenant Colonel Carl Jensen, and much of the battalion staff. Shattered, the 3rd Battalion was forced to withdraw in small groups, many of its soldiers already captured or forced to escape on foot through the countryside back to American lines. Most of the retreating men were also captured. Remaining soldiers formed a provisional company of 150 for the retreat. Ninety percent of the battalion's equipment, including weapons and helmets, was lost. Another four of the M24 tanks were also destroyed without disabling any of the North Korean T34s.

### Chochiwon falls

Under Smith, the 1st Battalion emplaced on hills overlooking the road into Chochiwon, resting the night of July 11 with no contact from the North Koreans until the next day. Just after dawn on July 12, the American battalion first encountered North Korean patrols. This was followed by an attack on their left flank by a North Korean force estimated as battalion-sized at 0930. Soon afterward, some 2,000 North Koreans began a direct assault on the 1st Battalion's position, supported by heavy artillery. Stephens decided the understrength battalion, with its large percentage of replacements, could not hold its position long and ordered it to withdraw. Smith subsequently moved the battalion from the line one company at a time, and the retreat was orderly. By nightfall, the entire regiment had moved by truck to a blocking position at Taepyong-ni, across the Kum River close to Taejon. In the meantime, U.S. forces on the westerly Kongju road fought a series of minor engagements to delay North Korean forces traveling down that road before retreating across the Kum River.

## Aftermath

The U.S. 21st Infantry Regiment suffered 228 killed, 61 wounded, 215 captured, and 27 missing in the battle; a total of 531 casualties. Of those, 130 of the captured and 20 of the missing died. Additionally, 23 other American units engaged in the region suffered 31 killed, 79 wounded, 15 captured, and 9 missing; in total, a further 134 casualties. This brought the total number of casualties for the three days to 665 and made Chochiwon the bloodiest battle for American forces yet in the conflict, greater than the casualty counts at Osan, Pyongtaek, and Chonan combined. The loss of materiel was also great, with the 21st Infantry Regiment losing enough equipment and materiel to outfit two rifle battalions and enough clothing to equip 975 men. Against these losses, North Korean casualties could not be estimated due to a lack of communication among fighting units, which limited the value of American signals intelligence.

Despite these losses, the U.S. 21st Infantry Regiment was praised for its efforts to defend Chochiwon and Chonui. Roy Appleman, a historian for the U.S. Army, called it "the most impressive performance yet of American troops in Korea." Indeed, the regiment delayed North Korean forces for three days in the fighting, despite suffering heavily in casualties and equipment losses, and in doing so, the action bought enough time for the rest of the 24th Infantry Division to set up defenses around Taejon. The 21st Infantry Regiment subsequently joined the 34th Infantry Regiment and the 19th Infantry Regiment in setting up positions along the Kum River near Taejon. The 24th Infantry Division would again be overrun and forced to retreat during the Battle of Taejon there over the next week. However, the delaying actions of the division would give the U.S. forces in Pusan time to set up the Pusan Perimeter, where the North Korean and UN forces would fight for several months in the Battle of Pusan Perimeter, eventually defeating the North Korean Army.

Part of the Korean War

Battles and operations of the Korean War in 1950

Battles of the Korean War involving North Korea

Battles of the Korean War involving the United States

Tank battles involving the United States


Astraeus hygrometricus

Astraeus hygrometricus, commonly known as the hygroscopic earthstar, the barometer earthstar, or the false earthstar, is a species of fungus in the family Diplocystaceae. Young specimens resemble a puffball when unopened. In maturity, the mushroom displays the characteristic earthstar shape that is a result of the outer layer of fruit body tissue splitting open in a star-like manner. The false earthstar is an ectomycorrhizal species that grows in association with various trees, especially in sandy soils. A. hygrometricus was previously thought to have a cosmopolitan distribution, though it is now thought to be restricted to Southern Europe, and Astraeus are common in temperate and tropical regions. Its common names refer to the fact that it is hygroscopic (water-absorbing), and can open up its rays to expose the spore sac in response to increased humidity, and close them up again in drier conditions. The rays have an irregularly cracked surface, while the spore case is pale brown and smooth with an irregular slit or tear at the top. The gleba is white initially, but turns brown and powdery when the spores mature. The spores are reddish-brown, roughly spherical with minute warts, measuring 7.5–11 micrometers in diameter.

Despite a similar overall appearance, A. hygrometricus is not related to the true earthstars of genus Geastrum, although historically, they have been taxonomically confused. The species was first described by Christiaan Hendrik Persoon in 1801 as Geastrum hygrometricus. In 1885, Andrew P. Morgan proposed that differences in microscopic characteristics warranted the creation of a new genus Astraeus distinct from Geastrum; this opinion was not universally accepted by later authorities. Several Asian populations formerly thought to be A. hygrometricus were renamed in the 2000s once phylogenetic analyses revealed they were unique Astraeus species, including A. asiaticus and A. odoratus. Similarly, in 2013, North American populations were divided into A. pteridis, A. morganii, and A. smithii on the basis of molecular phylogentics. This research suggests that the type specimen of Astraeus hygrometricus originates in a population restricted to Europe between Southern France and Turkey, with A. telleriae found nearby in Spain and Greece. Research has revealed the presence of several bioactive chemical compounds in Astraeus fruit bodies. North American field guides typically rate A. hygrometricus as inedible; while this may be accurate for the now-separate North American species, A. hygrometricus is commonly consumed in South and Southeast Asia.

## Taxonomy, naming, and phylogeny

Because this species resembles the earthstar fungi of Geastrum, it was placed in that genus by early authors, starting with Christian Hendrik Persoon in 1801 (as Geaster, an alternate spelling of Geastrum). According to the American botanist Andrew P. Morgan, however, the species differed from those of Geastrum in not having open chambers in the young gleba, having larger and branched capillitium threads, not having a true hymenium, and having larger spores. Accordingly, Morgan set Persoon's Geaster hygrometricum as the type species of his new genus Astraeus in 1889. Despite Morgan's publication, some authorities in the following decades continued to classify the species in Geastrum. The New-Zealand based mycologist Gordon Herriot Cunningham explicitly transferred the species back to the genus Geastrum in 1944, explaining:

> The treatment of this species by certain taxonomists well illustrates the pitfalls that lie in wait for those who worship at the shrine of ontogenic classification ... The only feature of those outlined in which the species differs from others of Geastrum is the somewhat primitive hymenium. In the developing plant the glebal cavities are separated by tramal plates so tenuous as to be overlooked by the uncritical worker. Each cavity is filled with basidia somewhat irregularly arranged in clusters (like those of Scleroderma) and not in the definite palisade of the species which have been studied. This difference disappears as maturity is reached, when plants resemble closely the fructification of any other member of the genus. The taxonomist is then unable to indicate any point of difference by which "Astraeus" may be separated from Geastrum, which indicates that the name should be discarded.

Cunningham's treatment was not followed by later authorities, who largely considered Astraeus a distinct genus. According to the taxonomical authority MycoBank, synonyms of Astraeus hygrometricus include Lycoperdon stellatus Scop. (1772); Geastrum fibrillosum Schwein. (1822); Geastrum stellatum (Scop.) Wettst. (1885); and Astraeus stellatus E.Fisch. (1900).

Astraeus hygrometricus has been given a number of colloquial names that allude to its hygroscopic behavior, including the "hygrometer earthstar", the "hygroscopic earthstar", the "barometer earthstar", and the "water-measure earthstar". The resemblance to Geastrum species (also known as true earthstars) accounts for the common name "false earthstar". The specific name is derived from the Greek words ὑγρός (hygros) 'wet' and μέτρον (metron) 'measure'. The German Mycological Society selected the species as their "Mushroom of the Year" in 2005.

Studies in the 2000s showed that several species from Asian collection sites labelled under the specific epithet hygrometricus were actually considerably variable in a number of macroscopic and microscopic characteristics. Molecular studies of the DNA sequences of the ITS region of the ribosomal DNA from a number of Astraeus specimens from around the world have helped to clarify phylogenetic relationships within the genus. Based on these results, two Asian "hygrometricus" populations have been described as new species: A. asiaticus and A. odoratus (synonymous with Petcharat's A. thailandicus described in 2003). Preliminary DNA analyses suggests that the European A. hygrometricus described by Persoon is a different species than the North American version described by Morgan, and that the European population may be divided into two distinct phylotypes, from France (A. hygrometricus) and from the Mediterranean (A. telleriae). A follow-up analysis from 2013 named two new North American species: A. morganii from the Southern US and Mexico and A. smithii from the Central and Northern United States, and grouped western US specimens in A. pteridis. A 2010 study identified a Japanese species, previously identified as A. hygrometricus, as genetically distinct; it has yet to be officially named.

A form of the species found in Korea and Japan, A. hygrometricus var. koreanus, was named by V.J. Stanĕk in 1958; it was later (1976) published as a distinct species—A. koreanus—by Hanns Kreisel. As pointed out by Fangfuk and colleagues, clarification of the proper name for this taxon must await analysis of A. hygrometricus var. koreanus specimens from the type locality in North Korea.

## Description

Young specimens of A. hygrometricus have roughly spherical fruit bodies that typically start their development partially embedded in the substrate. A smooth whitish mycelial layer covers the fruit body, and may be partially encrusted with debris. As the fruit body matures, the mycelial layer tears away, and the outer tissue layer, the exoperidium, breaks open in a star-shaped (stellate) pattern to form 4–20 irregular "rays". This simultaneously pushes the fruit body above ground to reveal a round spore case enclosed in a thin papery endoperidium. The rays open and close in response to levels of moisture in the environment, opening up in high humidity, and closing when the air is dry. This is possible because the exoperidium is made of several different layers of tissue; the innermost, fibrous layer is hygroscopic, and curls or uncurls the entire ray as it loses or gains moisture from its surroundings. This adaptation enables the fruit body to disperse spores at times of optimum moisture, and reduce evaporation during dry periods. Further, dry fruit bodies with the rays curled up may be readily blown about by the wind, allowing them to scatter spores from the pore as they roll.

The fruit body is 1–8 cm (0.5–3 in) in diameter from tip to tip when expanded. The exoperidium is thick, and the rays are typically areolate (divided into small areas by cracks and crevices) on the upper surface, and are dark grey to black. The spore case is sessile (lacking a stalk), light gray to tan color and 1 to 3 cm (0.4 to 1.2 in) broad with a felt-like or scurfy (coated with loose scaly crust) surface; the top of the spore case is opened by an irregular slit, tear or pore. The interior of the spore case, the gleba, is white and solid when young, and divided into oval locules—a characteristic that helps to distinguish it from Geastrum. The gleba becomes brown and powdery as the specimen matures. Small dark hairlike threads (rhizomorphs) extend from the base of the fruit body into the substrate. The rhizomorphs are fragile, and often break off after maturity.

The spores are spherical or nearly so, reddish-brown, thick-walled and verrucose (covered with warts and spines). The spores' dimensions are 7–11 μm; the warts are about 1 μm long. The spores are non-amyloid, and will not stain with iodine from Melzer's reagent. The use of scanning electron microscopy has shown that the spines are 0.90–1.45 μm long, rounded at the tip, narrow, tapered, and sometime joined at the top. The capillitia (masses of thread-like sterile fibers dispersed among the spores) are branched, 3.5–6.5 μm in diameter, and hyaline (translucent). The basidia (spore-bearing cells) are four- to eight-spored, with very short sterigmata. The basidia are arranged in long strings of clusters; individual basidia measure 11–15 by 18–24 μm. The threads of the capillitia arise from the inner surface of the peridium, and are thick-walled, long, interwoven, and branched, measuring 3–5.5 μm thick. The exoperidium (the outer layer of tissue, comprising the rays) is made of four distinct layers of tissue: the mycelial layer contains branched hyphae that are 4–6 μm in diameter; the hyphae of the fibrous layer are 6–8 μm diameter and branched; the collenchyma-type layer has branched hyphae of 3–4 μm diameter; the soft layer contains hyphae that are 3–6 μm in diameter.

### Edibility

North American sources list A. hygrometricus as inedible, in some cases because of its toughness. However, they are regularly consumed in Nepal and South Bengal, where "local people consume them as delicious food". They are collected from the wild and sold in the markets of India.

A study of a closely related southeast Asian Astraeus species concluded that the fungus contained an abundance of volatile eight-carbon compounds (including 1-octanol, 1-octen-3-ol, and 1-octen-3-one) that imparted a "mushroom-like, earthy, and pungent odor that was evident as an oily and moss-like smell upon opening the caps". The study's authors further noted that the fruit bodies after cooking have a "roasted, maillard, herbal, and oily flavor". Volatile compounds detected after cooking the mushroom samples included furfural, benzaldehyde, cyclohexenone, and furanyl compounds. The regional differences in opinions on edibility are from sources published before it was known that North American and Asian versions of A. hygrometricus were not always the same; in some cases Asian specimens have been identified as new species, such as A. asiaticus and A. odoratus.

## Similar species

Although A. hygrometricus bears a superficial resemblance to members of the "true earthstars" Geastrum, it may be readily differentiated from most by the hygroscopic nature of its rays. Hygroscopic earthstars include G. arenarium, G. corollinum, G. floriforme, G. recolligens, and G. kotlabae. Unlike Geastrum, the young fruit bodies of A. hygrometricus do not have a columella (sterile tissue in the gleba, at the base of the spore sac). Geastrum tends to have its spore sac opening surrounded by a peristome or a disc, in contrast with the single lacerate slit of A. hygrometricus. There are also several microscopic differences: in A. hygrometricus, the basidia are not arranged in parallel columns, the spores are larger, and the threads of the capillitia are branched and continuous with the hyphae of the peridium. Despite these differences, older specimens can be difficult to distinguish from Geastrum in the field. One species of Geastrum, G. mammosum, does have thick and brittle rays that are moderately hygroscopic, and could be confused with A. hygrometricus; however, its spores are smaller than A. hygrometricus, typically about 4 μm in diameter.

Astraeus pteridis is larger, 5 to 15 cm (2 to 6 in) or more when expanded, and often has a more pronounced areolate pattern on the inner surface of the rays. It is found in North America and the Canary Islands. A. asiaticus and A. odoratus are two similar species known from throughout Asia and Southeast Asia, respectively. A. odoratus is distinguished from A. hygrometricus by a smooth outer mycelial layer with few adhering soil particles, 3–9 broad rays, and a fresh odor similar to moist soil. The spore ornamentation of A. odoratus is also distinct from A. hygrometricus, with longer and narrower spines that often joined. A. asiaticus has an outer peridial surface covered with small granules, and a gleba that is purplish-chestnut in color, compared to the smooth peridial surface and brownish gleba of A. hygrometricus. The upper limit of the spore size of A. asiaticus is larger than that of its more common relative, ranging from 8.75 to 15.2 μm. A. koreanus (sometimes named as the variety A. hygrometricus var. koreanus; see Taxonomy) differs from the more common form in its smaller size, paler fruit body, and greater number of rays; microscopically, it has smaller spores (between 6.8 and 9 μm in diameter), and the spines on the spores differ in length and morphology. It is known from Korea and Japan.

## Habitat, distribution, and ecology

Astraeus hygrometricus is an ectomycorrhizal fungus and grows in association with a broad range of tree species. The mutualistic association between tree roots and the mycelium of the fungus helps the trees extract nutrients (particularly phosphorus) from the earth; in exchange, the fungus receives carbohydrates from photosynthesis. In North America, associations with oak and pine are usual, while in India, it has been noted to grow commonly with chir pine (Pinus roxburghii) and sal (Shorea robusta). The false earthstar is found on the ground in open fields, often scattered or in groups, especially in nutrient-poor, sandy or loamy soils. It has also been reported to grow on rocks, preferring acid substrates like slate and granite, while avoiding substrates rich in lime. In Nepal, fruit bodies have been collected at elevations of 3,000 m (9,800 ft). Fruit bodies typically appear in autumn, although the dry fruit bodies are persistent and may last up to several years. Gelatinipulvinella astraeicola is a leotiaceous fungus with minute, gelatinous, pulvinate (cushion-shaped) apothecia, known to grow only on the inner surface of the rays of dead Astraeus species, including A. hygrometricus.

The genus has a cosmopolitan distribution except for arctic, alpine and cold temperate regions; it is common in temperate and tropical regions of the world. It has been collected in Africa, Asia, Australia, Europe, North America, and South America.

## Bioactive compounds

Mushroom polysaccharides from a number of species have attracted research interest for their immunomodulatory and antitumor properties. Extracts from A. hygrometricus containing the polysaccharide named AE2 were found to inhibit the growth of several tumor cell lines in laboratory tests, and stimulated the growth of splenocytes, thymocytes, and bone marrow cells from mice. The extract also stimulated mouse cells associated with the immune system; specifically, it enhanced the activity of mouse natural killer cells, stimulated macrophages to produce nitric oxide, and enhanced production of cytokines. The activation of macrophages by AE2 might be mediated by a mitogen-activated protein kinase pathway of signal transduction. AE2 is made of the simple sugars mannose, glucose, and fucose in a 1:2:1 ratio.

In addition to the previously known steroid compounds ergosta-7,22-diene-3-ol acetate and ergosta-4,6,8-(14),22-tetraene-3-one, three unique triterpenes—derivatives of 3-hydroxy-lanostane—have been isolated from fruit bodies of A. hygrometricus. The compounds, named astrahygrol, 3-epi-astrahygrol, and astrahygrone (3-oxo-25S-lanost-8-eno-26,22-lactone), have δ-lactone (a six-membered ring) in the side chain—a chemical feature previously unknown in the basidiomycetes. A previously unknown steryl ester (3β, 5α-dihydroxy-(22E, 24R)-ergosta-7,22-dien-6α-yl palmitate) has been isolated from mycelia grown in liquid culture. The compound has a polyhydroxylated ergostane-type nucleus.

Ethanol extracts of the fruit body are high in antioxidant activity, and have been shown in laboratory tests to have anti-inflammatory activity comparable to the drug diclofenac. Studies with mouse models have also demonstrated hepatoprotective (liver-protecting) ability, possibly by restoring diminished levels of the antioxidant enzymes superoxide dismutase and catalase caused by experimental exposure to the liver-damaging chemical carbon tetrachloride.

## Traditional beliefs

This earthstar has been used in traditional Chinese medicine as a hemostatic agent; the spore dust is applied externally to stop wound bleeding and reduce chilblains. Two Indian forest tribes, the Baiga and the Bharia of Madhya Pradesh, have been reported to use the fruit bodies medicinally. The spore mass is blended with mustard seed oil, and used as a salve against burns. The Blackfoot of North America called the fungus "fallen stars", considering them to be stars fallen to the earth during supernatural events.

## See also

- Medicinal mushrooms

Cosmopolitan species of fungus in the family Diplocystaceae.

Taxa named by Christiaan Hendrik Persoon


Battle of Arawe

The Battle of Arawe (also known as Operation Director) was fought between Allied and Japanese forces during the New Britain campaign of World War II. The battle formed part of the Allied Operation Cartwheel and had the objective of serving as a diversion before a larger landing at Cape Gloucester in late December 1943. The Japanese military was expecting an Allied offensive in western New Britain and was reinforcing the region at the time of the Allied landing in the Arawe area on 15 December 1943. The Allies secured Arawe after about a month of intermittent fighting with the outnumbered Japanese force.

Initial Allied goals for the landing at Arawe included securing a base for American PT boats and diverting Japanese forces away from Cape Gloucester. The PT boat base was subsequently deemed unnecessary and was not built. Only a small Japanese force was stationed at Arawe at the time, although reinforcements were en route. The main Allied landing on 15 December was successful despite a failed subsidiary landing and problems coordinating the landing craft. American forces quickly secured a beachhead and dug in. Japanese air units made large-scale raids against the Arawe area in the days after the landing, and in late December Imperial Japanese Army (IJA) troops unsuccessfully counterattacked the American force. In mid-January 1944 the American force, reinforced with additional infantry and tanks, launched a brief offensive that pushed the Japanese back. The Japanese units at Arawe withdrew from the area towards the end of February as part of a general retreat from western New Britain.

There is no consensus among historians on whether the Allied offensive at Arawe was necessary. While some have argued that the landing served as a useful diversion ahead of the Cape Gloucester operation, others believe that the entire campaign in western New Britain was unnecessary and that the force employed at Arawe could have been better used elsewhere.

## Background

### Military situation

In July 1942, the U.S. Joint Chiefs of Staff directed that the main objective of the Allied forces in the South Pacific and Southwest Pacific area commands was to capture the major Japanese base at Rabaul on the eastern tip of New Britain. From August 1942, U.S. and Australian forces conducted a series of offensives in New Guinea and the Solomon Islands, with the goals of eliminating Japanese positions in the region and establishing air bases close to Rabaul. The Japanese forces in the area mounted a strong resistance but were unable to stop the Allied advance.

In June 1943 the Allies launched a major offensive—designated Operation Cartwheel—to capture Rabaul. During the next five months, Australian and U.S. forces under the overall command of General Douglas MacArthur advanced along the north coast of eastern New Guinea, capturing the town of Lae and the Huon Peninsula. U.S. forces under the command of Admiral William Halsey, Jr. simultaneously advanced through the Solomon Islands from Guadalcanal and established an air base at Bougainville in November 1943. In June 1943 the Joint Chiefs of Staff decided that it was unnecessary to capture Rabaul as the Japanese base there could be neutralized by blockade and aerial bombardment. MacArthur initially opposed this change in plans, but it was endorsed by the British and United States Combined Chiefs of Staff during the Quebec Conference in August 1943.

The Japanese Imperial General Headquarters assessed the strategic situation in the Southwest Pacific in late September 1943 and concluded that the Allies would attempt to break through the northern Solomon Islands and Bismarck Archipelago in the coming months en route to Japan's inner perimeter in the western and central Pacific. Accordingly, reinforcements were dispatched to strategic locations in the area in an attempt to slow the Allied advance. Strong forces were retained at Rabaul, however, as it was believed that the Allies would attempt to capture the town. At the time, Japanese positions in western New Britain were limited to airfields at Cape Gloucester on the island's western tip and several small way stations which provided small boats travelling between Rabaul and New Guinea with shelter from Allied aerial attacks.

On 22 September 1943 MacArthur's General Headquarters (GHQ) directed Lieutenant General Walter Krueger's Alamo Force to secure western New Britain and the surrounding islands. This operation had two goals, the first of which was to establish air and PT boat bases to attack the Japanese forces at Rabaul. The second objective was to secure the Vitiaz and Dampier Straits between New Guinea and New Britain so that convoys could safely pass through them en route to conduct further landings along New Guinea's north coast and beyond. To this end, GHQ directed that both Cape Gloucester and Gasmata on New Britain's south coast be captured. This offensive was code-named Operation Dexterity. The 1st Marine Division was selected for the Cape Gloucester operation, and the heavily reinforced 126th Regimental Combat Team from the 32nd Infantry Division was to attack Gasmata.

Senior Allied commanders disagreed over whether it was necessary to land forces in western New Britain. Lieutenant General George Kenney—commander of the Allied Air Forces in the Southwest Pacific—opposed the landings, arguing that his forces did not need air fields at Cape Gloucester as the existing bases in New Guinea and surrounding islands were adequate to support the planned landings in the region. Vice Admiral Arthur S. Carpender—commander of both the 7th Fleet and the Allied Naval Forces, Southwest Pacific Area—as well as Rear Admiral Daniel E. Barbey—commander of Task Force 76—supported occupying Cape Gloucester to secure both sides of the straits, but he opposed the landing at Gasmata as it was too close to the Japanese air bases at Rabaul. The Gasmata operation was cancelled in early November in response to the concerns raised by Kenney and the Navy as well as intelligence reports that the Japanese had reinforced their garrison there.

On 21 November, a conference between GHQ, Kenney, Carpender and Barbey was held in Brisbane at which it was decided to land a small force in the Arawe area. This operation had three goals: to divert Japanese attention from Cape Gloucester, to provide a base for PT boats, and to establish a defensive perimeter and make contact with the Marines once they landed. It was intended that PT boats operating from Arawe would disrupt Japanese barge traffic along the southern shore of New Britain and protect the Allied naval forces at Cape Gloucester from attack.

### Geography

The Arawe area lies on the south coast of New Britain about 100 mi (160 km) from the island's western tip. Its main geographical feature is Cape Merkus, which ends in the "L"-shaped Arawe Peninsula. Several small islands called the Arawe Islands lie to the southwest of the cape.

In late 1943, the Arawe Peninsula was covered by coconut trees which formed part of the Amalut Plantation; the terrain inland from the peninsula and on its offshore islands was swampy. Most of the shoreline in the area has limestone cliffs. There was a small unused airfield 4 mi (6.4 km) east of the neck of the Arawe Peninsula, and a coastal trail leading east from Cape Merkus to the Pulie River where it split into tracks running inland and along the coast. The terrain to the west of the peninsula was a trackless region of swamp and jungle, which was very difficult for troops to move through. Several of the beaches in the Arawe area were suitable for landing craft; the best were House Fireman, on the peninsula's west coast, and one near the village of Umtingalu to the east of the peninsula's base.

## Prelude

### Planning

Alamo Force was responsible for coordinating plans for the invasion of western New Britain. The Arawe landing was scheduled for 15 December as this was the earliest date by which the air bases around Nadzab in New Guinea—which were needed to support the landing—could be made operational. This date also gave the landing force time to conduct essential training and rehearsals. As Arawe was believed to be only weakly defended, Krueger decided to use a smaller force than the one which had been intended for the landing at Gasmata. This force, designated the Director Task Force, was concentrated at Goodenough Island where it was stripped of all equipment not needed for combat operations. Logistical plans called for the assault echelon to carry 30 day's worth of general supplies and enough ammunition for three days of intensive combat. After the landing, holdings would be expanded to 60 day's worth of general supplies and six day's worth of all categories of ammunition other than anti-aircraft ammunition, for which a 10-day supply was thought necessary. The assault force and its supplies were to be carried in fast ships which could rapidly unload their cargo.

The commander of the PT boat force in the Southwest Pacific, Commander Morton C. Mumma, opposed building extensive PT boat facilities at Arawe as he had sufficient bases and Japanese barges normally sailed along the north coast of New Britain. Mumma took his concerns to Admiral Arthur S. Carpender and Vice Admiral Daniel E. Barbey, who eventually agreed that he would not be required to establish a base there if he thought it unnecessary. Instead, Mumma assigned six boats stationed at Dreger Harbor in New Guinea and Kiriwina Island to operate along the south coast of New Britain east of Arawe each night, and he asked only for emergency refuelling facilities at Arawe.

The Director Task Force's commander—Brigadier General Julian Cunningham—issued orders for the landing on 4 December. He directed that the Task Force would initially capture the Arawe Peninsula and its surrounding islands and establish an outpost on the trail leading to the Pulie River. The main body was to land at House Fireman Beach on the Arawe Peninsula at about dawn. Two troop-sized forces would conduct separate operations about an hour before the main landing. One troop was to capture Pitoe Island to the peninsula's south, as it was believed that the Japanese had established a radio station and a defensive position there which commanded the entrance to Arawe Harbor. The other troop was to land at Umtingalu and establish a blocking position on the coastal trail east of the peninsula. Once the beachhead was secure, amphibious patrols would be conducted to the west of the peninsula in an attempt to make contact with the 1st Marine Division at Cape Gloucester. U.S. Navy personnel on the planning staff were concerned about these subsidiary landings, as a night-time landing conducted at Lae in September had proven difficult.

### Opposing forces

The Director Task Force was centered around the U.S. Army's 112th Cavalry Regimental Combat Team (112th RCT). This regiment had arrived in the Pacific in August 1942 but had not seen combat. It was dismounted and converted to an infantry unit in May 1943 and undertook an unopposed landing at Woodlark Island (designated Operation Chronicle) on 23 June. The 112th Cavalry Regiment was smaller and more lightly armed than U.S. infantry regiments as it had only two battalion-sized squadrons compared to the three battalions in infantry regiments. Moreover, the squadrons were smaller and more lightly equipped than their infantry equivalents. The 112th RCT's combat support units were the M2A1 howitzer-equipped 148th Field Artillery Battalion and the 59th Engineer Company. The other combat units of the Director Task Force were two batteries of the 470th Anti-aircraft Artillery Battalion (Automatic Weapons), most of the 236th Anti-aircraft Artillery Battalion (Searchlight), "A" Company of the United States Marine Corps 1st Amphibious Tractor Battalion and a detachment from the 26th Quartermaster War Dog Platoon. The 2nd Battalion of the 158th Infantry Regiment was held in reserve to reinforce the Director Task Force if required. Several engineer, medical, ordnance and other support units were scheduled to arrive at Arawe after the landing was completed. Cunningham requested a battery equipped with 90 mm (3.54 in) anti-aircraft guns, but none were available. The U.S. Navy's Beach Party Number 1 would also be landed with the Director Task Force and remain at Arawe until the beachhead was secured.

The Director Task Force was supported by Allied naval and air units. The naval force was drawn from TF 76 and comprised U.S. Navy destroyers USS Conyngham (Barbey's flagship), Shaw, Drayton, Bagley, Reid, Smith, Lamson, Flusser and Mahan and a transport group with destroyer transports USS Humphreys and Sands, the Australian landing ship infantry , landing ship dock USS Carter Hall, two patrol craft and two submarine chasers. The naval force also included a service group with three LSTs, three tugboats and the destroyer tender USS Rigel. United States Army Air Forces (USAAF) and Royal Australian Air Force (RAAF) units operating under the Fifth Air Force would support the landing, but only limited air support was to be available after 15 December as the available aircraft were needed for strategic missions against Japanese bases.

Australian coastwatchers stationed on New Britain were reinforced during September and October 1943 to provide warning of air attacks from Rabaul bound for the Allied landing sites and to report on Japanese barge and troop movements. In addition to a coastwatching team already in place at Cape Orford near Wide Bay, five other parties were sent to Cape Hoskins, Gasmata, Open Bay (on the north coast at the base of the Gazelle Peninsula), the area south of Wide Bay, and the neck between Wide Bay and Open Bay. The Gasmata party was discovered by the Japanese while en route to its destination and eliminated, but the other teams were in place by the end of October.

At the time of the Allied landing, the Arawe area was defended by only a small force, though reinforcements were en route. The Japanese force at Arawe comprised 120 soldiers and sailors organized in two temporary companies drawn from the 51st Division. The reinforcing units were elements of the 17th Division, which had been shipped from China to Rabaul during October 1943 to reinforce western New Britain ahead of the expected Allied invasion. The convoys carrying the division were attacked by U.S. Navy submarines and USAAF bombers and suffered 1,173 casualties. The 1st Battalion, 81st Infantry Regiment was assigned to defend Cape Merkus. However, it did not depart Rabaul until December as it needed to be reorganized after suffering casualties when the ship transporting it from China was sunk. In addition, two of its rifle companies, most of its heavy machine guns and all its 70 mm (2.76 in) howitzers were retained by the 8th Area Army at Rabaul, leaving the battalion with just its headquarters, two rifle companies and a machine gun platoon. This battalion—which came under the command of Major Masamitsu Komori—was a four-day march from Arawe when the Allies landed. A company of soldiers from the 54th Infantry Regiment, some engineers and detachments from other units were also assigned to the Arawe area. The ground forces at Arawe came under the overall command of General Matsuda, whose headquarters were located near Cape Gloucester. The Japanese air units at Rabaul had been greatly weakened in the months prior to the landing at Arawe by prolonged Allied attacks and the transfer of the 7th Air Division to western New Guinea. Nevertheless, the Imperial Japanese Navy's (IJN) 11th Air Fleet had 100 fighters and 50 bombers based at Rabaul at the time of the landing at Arawe.

### Preliminary operations

The Allies possessed little intelligence on western New Britain's terrain and the locations of Japanese forces, so they flew extensive air photography sorties over the region, and small ground patrols were landed from PT boats. A team from Special Service Unit No. 1 reconnoitered Arawe on the night of 9/10 December and concluded that there were few Japanese troops in the area. The Japanese detected this party near the village of Umtingalu and strengthened their defenses there.

Operation Dexterity was preceded by a major Allied air offensive which sought to neutralize the Japanese air units stationed at Rabaul. From 12 October until early November, the Fifth Air Force frequently attacked the airfields around the town as well as ships in its harbor. Aircraft flying from U.S. Navy aircraft carriers also attacked Rabaul on 5 and 11 November in support of the USMC's landing at Bougainville.

The Allied air forces began pre-invasion raids on western New Britain on 13 November. Few attacks were made on the Arawe area, however, as the Allies hoped to achieve tactical surprise for the landing and did not want to alert the Japanese to their intentions. Instead, heavy attacks were made against Gasmata, Ring Ring Plantation and Lindenhafen Plantation on New Britain's south coast. The Arawe area was struck for the first time on 6 December and again on 8 December; little opposition was encountered on either occasion. It was not until 14 December—the day before the landing—that heavy air attacks on Arawe were conducted; Allied aircraft flew 273 sorties against targets on New Britain's south coast that day. In addition to these air raids, a force comprising two Australian and two American destroyers (designated Task Force 74.2) bombarded the Gasmata area during the night of 29/30 November.

The Director Task Force was concentrated at Goodenough Island in early December 1943. The 112th Cavalry was notified that it had been selected for the Arawe operation on 24 November and departed Woodlark for the short voyage to Goodenough Island in two convoys that sailed on 30 and 31 November. All elements of the regiment were ashore at Goodenough by 2 December. A full-scale rehearsal of the landing was held at the island on 8 December; this revealed problems with coordinating the waves of boats and demonstrated that some of the force's officers were insufficiently trained in amphibious warfare. There was insufficient time for further training to rectify these problems, however. At Goodenough, the troopers of the 112th Cavalry were issued with several types of infantry weapons with which they had not previously been equipped. Each of the regiment's rifle squads received a Browning Automatic rifle and a Thompson submachine gun; 2.36-inch (6.0 cm) bazookas, rifle grenades and flame throwers were also issued. The cavalrymen received little training on the use of these weapons and did not know how to make the best use of them in combat.

The invasion force boarded transport ships during the afternoon of 13 December, and the convoy sailed at midnight. It proceeded to Buna to rendezvous with most of the escorting destroyers and made a feint north toward Finschhafen before turning toward Arawe after dusk on 14 December. The convoy was detected by a Japanese aircraft shortly before it anchored off Arawe at 03:30 on 15 December, and the 11th Air Fleet at Rabaul began to prepare aircraft to attack it.

## Battle

### Landings

Shortly after the assault convoy arrived off Arawe, Carter Hall launched LVT amphibious tractors and Westralia lowered landing craft, both operated by specialized Marine and U.S. Army units. The two large transports departed for New Guinea at 05:00. The high speed transports carrying "A" and "B" Troops of the 112th Cavalry Regiment's 1st Squadron closed to within 1,000 yd (910 m) of Umtingalu and Pilelo Island respectively, and unloaded the soldiers into rubber boats.

"A" Troop's attempt to land at Umtingalu ended in failure. At about 05:25 the troop came under fire from machine guns, rifles and a 25 mm (0.98 in) cannon as it was nearing the shore, and all but three of its 15 rubber boats were sunk. Shaw—the destroyer assigned to support the landing—was unable to fire upon the Japanese positions until 05:42 as her crew initially could not determine if the soldiers in the water were in the ship's line of fire. Once she had a clear shot, Shaw silenced the Japanese force with two salvos from her 5 in (130 mm) guns. The surviving cavalrymen were rescued by small boats and later landed at House Fireman beach; casualties in this operation were 12 killed, four missing and 17 wounded.

The landing conducted by "B" Troop at Pilelo Island was successful. The goal of this operation was to destroy a Japanese radio station believed to be at the village of Paligmete on the island's east coast. The troop was originally intended to come ashore near Paligmete, but the landing site was switched to the island's west coast after "A" Troop came under attack. After disembarking from their boats, the cavalrymen advanced east and came under fire from a small Japanese force stationed in two caves near the village of Winguru on the island's north coast. Ten cavalrymen were detached to contain the Japanese while the remainder of the troop continued to Paligmete. The village proved to be unoccupied and did not contain the suspected radio station. The majority of "B" Troop then attacked Winguru using bazookas and flamethrowers to destroy the Japanese positions. One American and seven Japanese soldiers were killed in the fighting. Personnel from the RAAF's No. 335 Radar Station also landed on Pilelo Island on 15 December and established a radar station there within 48 hours.

The 2nd Squadron, 112th Cavalry Regiment made the main landing at House Fireman Beach. The landing was delayed by a strong current and difficulties forming the LVTs into an assault formation, and the first wave went ashore at 07:28 rather than 06:30 as planned. Destroyers bombarded the beach with 1,800 rounds of 5 inch ammunition between 06:10 and 06:25, and B-25 Mitchells strafed the area once the bombardment concluded, but the landing area was not under fire as the troops approached the beach. This allowed Japanese machine gunners to fire on the LVTs, but these guns were rapidly silenced by rockets fired from SC-742 and two DUKWs. The first wave of cavalrymen were fortunate to meet little opposition as there were further delays in landing the follow-up waves owing to differences in the speeds of the two types of LVTs used. While the four follow-up waves were scheduled to land at five-minute intervals after the first wave, the second landed 25 minutes after the initial force, and the succeeding three waves landed simultaneously 15 minutes later. Within two hours of the landing, all the large Allied ships other than Barbey's flagship had departed from Arawe. Conyngham remained in the area to rescue the survivors of the landing at Umtingalu and withdrew later that day.

Once ashore, the cavalrymen rapidly secured the Arawe Peninsula. An American patrol sent to the peninsula's toe met only scattered resistance from Japanese rear guards. More than 20 Japanese located in a cave on the east side of the peninsula were killed by members of "E" Troop and personnel from the squadron headquarters; the remaining Japanese units in the area retreated to the east. The 2nd Squadron reached the peninsula's base at 14:30, where it began to prepare its main line of resistance (MLR). By the end of 15 December, more than 1,600 Allied troops were ashore. The two Japanese Army companies that had been stationed at Arawe withdrew to the northeast and took up positions at Didmop on the Pulie River about 8 mi (13 km) from the MLR; the naval unit defending Umtingalu retreated inland in a state of disarray.

The Allied naval force off Arawe was subjected to a heavy air raid shortly after the landing. At 09:00 eight Aichi D3A "Val" dive bombers escorted by 56 A6M5 "Zero" fighters evaded the USAAF combat air patrol of 16 P-38 Lightnings. The Japanese force attacked the recently arrived first supply echelon, which comprised five Landing Craft Tank and 14 Landing Craft Medium, but these ships managed to evade the bombs dropped on them. The first wave of attackers suffered no losses, but at 11:15 four P-38s shot down a Zero, and at 18:00 a force of 30 Zeros and 12 Mitsubishi G4M3 "Betty" and Mitsubishi Ki-21-II "Sally" bombers was driven off by four P-38s. The Japanese lost two Zeros in the day's air actions, but both pilots survived.

### Air attacks and base development

Although the U.S. ground troops faced no opposition in the days immediately after the landing, naval convoys carrying reinforcements to the Arawe area were repeatedly attacked. The second supply echelon came under continuous air attack on 16 December, resulting in the loss of APc-21 as well as damage to SC-743, YMS-50 and four LCTs. About 42 men on board these ships were killed or seriously wounded. Another reinforcement convoy was attacked three times by dive bombers on 21 December as it unloaded at Arawe. Overall, at least 150 Japanese aircraft attacked Arawe that day. Further air attacks took place on 26, 27 and 31 December. However, the Allied air forces were able to mount a successful defense of the Arawe area as the coastwatcher parties in New Britain provided 30 to 60 minutes warning of most incoming raids. Between 15 and 31 December, at least 24 Japanese bombers and 32 fighters were shot down near Arawe. During the same time period, Allied air units also raided airfields at Rabaul and Madang in New Guinea which were believed to be the bases of the aircraft which had attacked Arawe. In aerial combat over Rabaul on 17, 19, and 23 December, 14 Zeros were shot down by Allied aircraft. The process of unloading ships at Arawe was hampered by air attacks and congestion on House Fireman Beach. The beach party contributed to these delays as it was inexperienced and too small. The resultant problems with unloading LCTs caused some to leave the area before discharging all their cargo.

Air attacks on Arawe dropped off after 1 January 1944. As a result of the heavy losses they suffered during attacks on Arawe and Cape Gloucester, and the damage caused by Allied raids on Rabaul, Japanese air units conducted only small-scale raids at night after this date. The IJN fighter units based at Rabaul and nearby Kavieng were also kept busy throughout January and February defending their bases from continuous Allied air attacks. Few raids were made against the Arawe area after 90 mm anti-aircraft guns were established there on 1 February. These weak attacks did not disrupt the Allied convoys. In the three weeks after the landing, 6,287 short tons (5,703 t) of supplies as well as 541 artillery guns and vehicles were transported to Arawe. On 20 February, the Japanese air units at Rabaul and Kavieng were permanently withdrawn to Truk, ending any significant aerial threat to Allied forces in New Britain from the IJN.

Following the landing, the 59th Engineer Company constructed logistics facilities in the Arawe area. Because of the Japanese air raids, priority was given to the construction of a partially underground evacuation hospital, which was completed in January 1944. The underground hospital was replaced with a 120-bed above-ground facility in April 1944. Pilelo Island was selected for the site of the PT boat facilities, and a pier for refueling the boats and dispersed fuel storage bays were built there. A 172 ft (52 m) pier was constructed at House Fireman Beach between 26 February and 22 April 1944 to accommodate small ships; three LCT jetties were also built north of the beach. A 920 ft (280 m) by 100 ft (30 m) airstrip was hurriedly built for artillery observation aircraft on 13 January, and this was later upgraded and surfaced with coral. The engineer company also constructed 5 mi (8.0 km) of all-weather roads in the Arawe region and provided the Director Task Force with water via salt water distillation units on Pilelo Island and wells dug on the mainland. These projects were continuously hampered by shortages of construction materials, but the engineers were able to complete them by improvising and making use of salvaged material.

The 112th Cavalry RCT strengthened its defensive positions during the week following the invasion. As "A" Troop had lost all of its weapons and other equipment during the landing attempt at Umtingalu, supplies were air-dropped into the beachhead during the afternoon of 16 December to re-equip the unit. The troop was also assigned 50 replacement personnel. Most of "B" Troop was also transferred from Pilelo Island to the mainland in the days after the landing. The regiment improved its MLR by removing vegetation in order to create clear fields of fire, establishing minefields and wire entanglements and laying down a field telephone network. A reserve defensive line was also established closer to Cape Merkus, and patrols were conducted each day along the shores of the peninsula in search of Japanese personnel attempting to infiltrate the Task Force's rear area. These patrols located and killed between ten and twenty Japanese near Cape Merkus. In addition, the regiment established a network of observation posts throughout the Arawe area; these included positions in villages, key positions on the peninsula and on several offshore islands. "G" Troop was assigned to secure Umtingalu, and after doing so the troop established a patrol base at the village as well as two observation posts along the track which connected it to the MLR.

### Japanese response

The commander of the Japanese 17th Division—Lieutenant General Yasushi Sakai—ordered that Arawe be urgently reinforced when he was informed of the landing there. He did not believe that this would be the main Allied effort in western New Britain, however. The force under Komori was ordered to make haste. The 1st Battalion, 141st Infantry Regiment, stationed at Cape Bushing on the south coast of New Britain about 40 mi (64 km) east of Arawe, was also directed to move by sea to counter the Allied invasion. One of this battalion's infantry companies remained at Cape Bushing. Komori was appointed the commander of all Japanese forces in the Arawe area, which were subsequently designated the Komori Force. The 1st Battalion, 141st Infantry Regiment landed at the village of Omoi on the night of 18 December and started overland the next day to link up with Komori at Didmop. The battalion took eight days to cover the 7 mi (11 km) between Omoi and Didmop as it became lost on several occasions while travelling through trackless jungle and paused whenever contact with American forces seemed likely. Komori reached Didmop on 19 December and gathered the units that had retreated from Umtingalu into his command. On the basis of discussions with personnel who had witnessed the landing at Arawe, Komori mistakenly concluded that they had greatly overestimated the size of the Allied force. As a result, on 20 December he decided to launch a counteroffensive against the American positions.

After establishing its beachhead, the Director Task Force conducted a series of reconnaissance patrols. Cunningham had been ordered to gather intelligence on Japanese forces in western New Britain, and on 17 December he dispatched a patrol of cavalrymen in two LCVPs (Landing Craft, Vehicle, Personnel) to the west of Arawe to investigate the Itni River area. These landing craft encountered seven Japanese barges carrying part of the 1st Battalion, 141st Infantry Regiment near Cape Peiho, 20 mi (32 km) west of Arawe, on 18 December. After an exchange of gunfire the U.S. soldiers abandoned their landing craft and returned to Arawe along the coast. Another patrol travelling in LCVPs was fired on by Japanese barges near Umtingalu on 18 December but was able to return to Cape Merkus. Japanese barges were also sighted near Arawe on 23 December. Cunningham believed that a large Japanese force was heading for the beachhead and contacted Krueger on 24 December to request that the 2nd Battalion of the 158th Infantry Regiment be dispatched to reinforce his command. Krueger agreed to this request and ordered that three of the battalion's four infantry companies be sent to Arawe. "G" Company of the 2nd Battalion, 158th Infantry arrived on 27 December and the other two companies reached Arawe in early January.

After organizing his force while waiting for the 1st Battalion, 141st Infantry Regiment, Komori began his advance on Arawe on 24 December. He arrived at the airstrip to the north of Arawe during the early hours of Christmas Day. During that morning, elements of the Komori Force ambushed two platoon-sized American patrols traveling in trucks northeast of Umtingalu. The American units withdrew to the village and reinforced "G" Troop's defensive position there. The American force defeated several Japanese attempts to move around Umtingalu during the day and killed at least three enemy soldiers. Cunningham believed that the force encountered around Umtingalu was the advance guard of a much larger body of Japanese soldiers advancing from Gasmata and so withdrew the troops stationed around the village to positions behind the MLR. At 22:30 that night, 50 Japanese soldiers made a poorly coordinated attack on the MLR. While they succeeded in overrunning some American positions, the Japanese were repulsed by fire from the 112th Cavalry's 60-millimeter (2.4 in) mortars. The Americans lost one man killed and eight wounded, and the Japanese suffered twelve casualties.

The Japanese offensive continued after the Christmas Day attack. Two small attacks, each involving 15 soldiers, were made against the eastern edge of the MLR on the nights of 26 and 27 December. These were also repulsed by the 112th Cavalry's light mortars and inflicted only a small number of casualties on the American force. On 28 December part of the 112th Cavalry Regiment's "B" Troop set out from the MLR in an attempt to reach Umtingalu but withdrew after encountering snipers and some light mortar fire. A platoon from "C" Troop also made an unsuccessful patrol from the western end of the MLR during which it suffered six casualties from Japanese machine gun and rifle fire. The same day Komori dispatched a force of between 20 and 30 soldiers to destroy the American mortar positions. The Japanese soldiers infiltrated the American positions by wading through swamps at the western end of the MLR but were detected before they could reach dry land. The Director Task Force mounted a strong response which included a counterattack by elements of three cavalry troops and a platoon from the 158th Infantry Regiment supported by mortars. The Japanese force suffered 17 casualties.

The 1st Battalion, 141st Infantry Regiment arrived in the Arawe area on the afternoon of 29 December and conducted several small and unsuccessful attacks in early January before taking up positions about 400–500 yd (370–460 m) north of the American MLR. These positions comprised shallow trenches and foxholes which were difficult to see. Although there were only about 100 Japanese soldiers in the area, they moved their six machine guns frequently, making them difficult targets for American mortars and artillery.

### American counter-attack

An American patrol located the Japanese defensive position on 1 January 1944. "B" Troop of the 112th Cavalry Regiment launched an attack later that morning but was beaten off by heavy fire; the Americans suffered three killed and 15 wounded in this action. On 4 January "G" Troop incurred three killed and 21 wounded in an unsuccessful attack on well-built Japanese positions. This operation had been conducted without artillery support in an attempt to surprise the Japanese and also included a feint against Umtingalu involving several LCMs. Further attacks on 6, 7 and 11 January failed to make any headway but gave the cavalrymen experience in maneuvering through the Japanese defensive positions. These American operations were conducted on a limited scale as Cunningham and the 112th Cavalry Regiment's other senior officers believed that the unit had already achieved the goals of the landing at Arawe and did not want to incur unnecessary casualties.

On 6 January Cunningham requested further reinforcements, including tanks, to tackle the Japanese defenses. Krueger approved this request and ordered "F" Company, 158th Infantry Regiment and "B" Company of the USMC 1st Tank Battalion to Arawe; the two units arrived on 10 and 12 January respectively. The Marine tanks and two companies of the 158th Infantry Regiment subsequently practiced tank-infantry cooperation from 13 to 15 January; during this period the 112th Cavalry continued to conduct patrols into Japanese-held areas. By this time, the Komori Force had incurred casualties of at least 65 killed, 75 wounded and 14 missing in action as a result of its offensive actions as well as the attacks on it conducted by the Director Task Force. The Japanese were also suffering from severe supply shortages and an outbreak of dysentery.

The Director Task Force launched its attack on 16 January. That morning, a squadron of B-24 Liberator heavy bombers dropped 136 bombs on the Japanese defenses, and 20 B-25s strafed the area. Following an intensive artillery and mortar barrage the Marine tank company, two companies of the 158th Infantry and C Troop, 112th Cavalry Regiment attacked. The tanks led the advance, with each being followed by a group of infantrymen. The cavalry troop and three tanks were initially held in reserve but were sent into action at 12:00 to mop up a Japanese position. The attack was successful and reached its objectives by 16:00. Cunningham then directed the force to withdraw to the MLR; during this part of the operation two Marine tanks—which had become immobile—were destroyed to prevent the Japanese from using them as pillboxes. American engineers destroyed the Japanese defensive position the next day. The Director Task Force suffered 22 killed and 64 wounded in this operation and estimated that 139 Japanese had been killed.

Following the American attack, Komori pulled his remaining force back to defend the airstrip. As this was not an Allied objective, the Japanese were not subjected to further attacks by ground troops other than occasional patrol clashes and ambushes. As a result of the supply shortages, many of the Japanese soldiers fell sick. Attempts to bring supplies in by sea from Gasmata were disrupted by U.S. Navy PT boats, and the force lacked enough porters to supply itself through overland trails. Komori concluded that his force was serving no purpose and on 8 February informed his superiors that it faced destruction because of supply shortages. They responded by ordering Komori to hold his positions, though his force was awarded two Imperial citations in recognition of its supposed success in defending the airstrip.

## Aftermath

The 1st Marine Division's landing at Cape Gloucester on 26 December 1943 was successful. The Marines secured the airfields that were the main objective of the operation on 29 December against only light Japanese opposition. Heavy fighting took place during the first two weeks of 1944 when the Marines advanced south to the east of their initial beachhead to secure Borgen Bay. Little fighting took place once this area had been captured, and the Marines patrolled extensively in an attempt to locate the Japanese. On 16 February a Marine patrol from Cape Gloucester made contact with an Army patrol from Arawe at the village of Gilnit. On 23 February the remnants of the Japanese force at Cape Gloucester were ordered to withdraw to Rabaul.

The Komori Force was also directed to withdraw on 24 February as part of the general Japanese retreat from western New Britain. The Japanese immediately began to leave their positions and head north along inland trails to join other units. The Americans did not detect this withdrawal until 27 February, when an attack conducted by the 2nd Squadron, 112th Cavalry and the Marine tank company to clear the Arawe area of Japanese encountered no opposition. The Director Task Force subsequently established observation posts along the southern coast of New Britain and increased the distances covered by its reconnaissance patrols.

Komori fell behind his unit and was killed on 9 April near San Remo on New Britain's north coast when he, his executive officer, and two enlisted men they were travelling with were ambushed by a patrol from the 2nd Battalion, 5th Marines, which had landed around Volupai and captured Talasea on the Willaumez Peninsula in early March.

The Japanese force at Arawe suffered much heavier casualties than the Allies. The Director Task Force's total casualties between 15 December 1943 and the end of major fighting in the area were 118 dead, 352 wounded, and four missing. Most of these casualties were members of the 112th Cavalry Regiment, which suffered 72 killed, 142 wounded and four missing. Japanese casualties over this period were 304 men killed and three captured.

In the period immediately after the Japanese withdrawal, the Director Task Force remained at Arawe. In line with standard practice, the 112th Cavalry continued to improve the defensive positions in the area. The regiment also undertook training, and some men were granted leave to Australia and the United States. Combat patrols continued to be conducted in the Arawe region in search of Japanese stragglers. Elements of the 40th Infantry Division began to arrive at Arawe in April 1944 to assume responsibility for garrisoning the area. The 112th Cavalry Regiment was informed that it was to be deployed in New Guinea in early June, and the Director Task Force was dissolved at this time. The regiment sailed for the Aitape area of New Guinea on 8 June and next saw combat there during the Battle of Driniumor River. The 40th Infantry Division maintained a garrison at Arawe until the Australian Army's 5th Division assumed responsibility for New Britain in late November 1944.

Historians disagree over whether the Arawe operation was worthwhile for the Allies. The official history of the USMC in World War II stated that the presence of two experienced Japanese battalions at Arawe made the 1st Marine Division's task at Cape Gloucester easier. However, Samuel Eliot Morison writes that "Arawe was of small value" as the Allies never used it as a naval base and the garrison stationed in the area after the landings would have been better employed elsewhere. The U.S. Army's official history concluded that in retrospect the landings at Arawe and Cape Gloucester "were probably not essential to the reduction of Rabaul or the approach to the Philippines", though the offensive in western New Britain had some benefits and was not "excessively high in casualties".

WWII battle in the Pacific Theater

Amphibious operations involving the United States

Battles and operations of World War II involving Papua New Guinea

Battles of World War II involving Australia

Battles of World War II involving the United States

South West Pacific theatre of World War II

United States Marine Corps in World War II