1827 naval battle of the Cisplatine War
The naval Battle of Juncal took place between a squadron of the newly independent United Provinces of the River Plate under command of William Brown and a squadron belonging to the Brazilian Empire, commanded by Sena Pereira. It spanned two days, from 8 to 9 February 1827, in the waters of the Río de la Plata.
The two squadrons were initially of roughly equal strength, but because of superior command and control, and gunnery training, the Argentines scored a decisive victory: out of 17 Brazilian vessels, 12—including the flagship with its admiral—were captured and 3 were burnt. Not a single Argentine vessel was lost.
In the aftermath of the battle, the Third Division, the arm of the Brazilian fleet tasked with controlling the Uruguay River and thus disrupting communications with the Argentine army then operating in the Cisplatina province, was completely destroyed. The result was the biggest naval victory for Argentina in the Cisplatine War.
The situation before the battle.
The divisions of the imperial fleet.
During the second year of the Cisplatine War, the Brazilians took advantage of their numerical superiority on sea and divided their naval forces operating in the Río de la Plata sector into three squadrons, or "divisions".
First Argentine advance.
To confront the three threats, each of similar or superior strength to his own forces, the Argentine commander, William Brown, acted rapidly to organize a squadron to advance past the mouth of the Uruguay River, then find and destroy the Third Division.
 Simultaneously, to stop reinforcements from arriving from the Mariath Division and to secure his rear, he moved to fortify the island of Martin Garcia (called the "Fortress of the Constitution") while he left the defense of the Buenos Aires coast to his flagship, the brig "Independencia", along with the brig "Republica", the barque "Congreso", and four gunboats under the command of Leonardo Rosales.
Typical of Brown's audacity, the force he dispatched was in the best case only the equal of the Third Division, while the defense of Buenos Aires was clearly imperiled.
The Argentine squadron sailed on 26 December 1826, arriving on the Uruguay River on 28 December. After finding the Third Division, the squadron chased it, catching it in the Yanguari the next day. Brown sent John Halstead Coe, captain of "Sarandí" to the Brazilian commander as an emissary to request the Brazilians to surrender. Sena Pereira responded by taking Coe prisoner and joining the battle, which lasted until 30 December. However, due to the lack of wind and the narrowness of the channel maneuvering was difficult and the fighting was inconclusive.
Unable from gaining access to the narrow channel, Brown withdrew to the south towards Punta Gorda to await the Brazilians. He landed a small force on the Vizcaino Island to secure it and sent instructions to the militia of Santo Domingo de Soriano to cut supplies to the Brazilian fleet. In response, the Brazilians withdrew further north to Concepción del Uruguay (then still usually called "Arroyo de la China") where they could secure supplies.
Worried about the menace that the Mariath Division posed to his rear, Brown decided to fully return to Buenos Aires in search of reinforcements for Martin Garcia Island. He ordered Rosales to return the "Sarandí" to Uruguay via the Paraná de las Palmas while he finished the preparations, after which he rejoined the fleet by travelling aboard a small whaler.
Preparations.
On 6 January the fortification work was begun. The Mariath Division launched an advance on the island with the corvette "Maceió" and nine other gunships. On 18 January Brown twice ordered his forces out to meet the Brazilian squadron and both times the Brazilians withdrew after an exchange of cannon fire.
Brown wanted on one side to lure the Third Division into combat, yet at the same time he did not want the Mariath Division to join the Third or attack his rear. Helping him navigate the delicate situation was an excellent intelligence network which gave him daily updates on the movement of the Imperial fleet. Essentially, the emissary carrying Rodrigo Pinto Guedes' orders to Sena Pereira had been co-opted by Argentine patriots in Montevideo and as a result Brown received timely news of the Imperial fleet's intentions. Thus, he took notice when Pinto Guedes informed Sena Pereira of the orders given to Frederico Mariath to advance towards the south. Brown deduced that the Third Division would descend the river on 7 February in order to link up with Mariath. Brown believed that the fortifications and batteries of Martin Garcia would be ready by then, allowing him to block the Mariath Division while forcing the Third Division into battle.
The work at the new fort was duly accelerated; Brown himself worked as a master mason in the hold of "Santa Barbara". On 5 February, the works were ready and in a solemn ceremony Brown named the fort "Constitución". In his speech to the garrison, he informed them that he expected the Argentine squadron to meet Sena Pereira within the next couple days.
At the beginning of February there was word that the Third Division was taking on provisions at Arroyo de la China; by the third it had passed Paysandú and on 6 February it approached Higuerita (today's Nueva Palmira) where it arrived the next day. That same day, Brown outlined his plan and assigned each ship a role in the battle. At 10 pm, the vanguard of the Argentine fleet reached the mouth of the Paraná Guazú river and waited for the rest of the fleet to arrive.
The battle.
Combatants.
Argentina (Brown).
15 vessels, 73 guns, approximately 750 men
Brazil (Pereira).
17 vessels, about 750 men
The Argentine squadron numbered 15 vessels, including three major ships: the flagship goleta under the direct command of Brown, the goleta "Maldonado" under the command of the young Francisco Drummond—fiance of Brown's daughter—and "Bergantín Balcarce", with 14 cannon and under the command of Francisco José Seguí. Rounding out the squadron were the schooners "La Pepa", under Calixto Silva, "Guanaco" (Guillermo Enrique Granville), "Unión" (Shannon Malcolm), the smack "Uruguay" (Guillermo Mason), and eight gunboats. In total, 69 cannon and a crew of approximately 750 men.
The Brazilian squadron included 17 vessels: the flagship goleta "Oriental" under the command of Jacinto Roque de Sena Pereira, "Bergantín Dona Januária" under Pedro Antonio Carvalho, the goleta "Bertioga" under Lieutenant George Broom, "Liberdade do Sul" under Lieutenant Augusto Venceslau da Silva Lisboa, "12 de Outubro", the goleta "Fortuna" (a hospital ship), "Goleta Vitoria de Colonia", the goleta "Itapoã" under the command of lieutenant Germano Máximo de Souza Aranha, the goleta "7 de Março", the goleta "Brocoió" under Francisco de Paula Osório, the goleta "9 de Janeiro", the goleta "7 de Setembro", two gun schooners ("Atrevida" and "Paraty") and the "cañoneras" "Cananéia", "Paranaguá", and "Iguapé". In total, 65 guns and approximately 750 men. For the first and only time during the war, there was relative parity between the forces, or at least, the Brazilian advantage was not so great.
Approach of the fleets.
The Argentine squadron spent the night of 7 February anchored between Juncal Island and the west bank of the river. At dawn on 8 February the sails of the Brazilians were spotted descending the river, taking advantage of a gentle north wind. Brown gave the order to weigh anchor and placed his ships in a line of battle arrayed obliquely to the southeast from Juncal Island. The "goleta" "Sarandi" formed the center of the line, with "Maldonando" in the vanguard and "Balcarce" in the rear.
The Brazilian fleet continued its advance until the wind died down around 11:30 am, at which point it anchored some from the Argentine line, with the flagship "Oriental" in the center.
Beginning of the battle.
The weather on 8 February was stormy, hot and humid, with light and variable winds; typical for that time of year in the litoral regions. Sena Pereira anchored his ships and unleashed a fire ship toward the enemy fleet. However, this was promptly sunk by Argentine gunfire.
At noon Brown ordered forward a detachment of six of his gunboats, which could fire at a longer range than his other vessels with their guns. However the Argentine long guns had longer range and were manned by superior gunners. After exchanging fire for approximately two hours, a sudden "sudestada" (Sudestada (Southeast blow) is the Spanish name for a climatic phenomenon common to the Río de la Plata) separated the fleets and forced them to suspend the battle.
The Brazilians maintained the dominant, windward position; because the wind was blowing towards the Argentines, the Brazilians had the initiative. Sena Pereira duly tried to stage his ships in an attack line. However, the maneuvers of the vessels were disastrous: the goleta "Liberdade do Sul" grounded, while "Dona Januária" left the formation and strayed within range of the fire of "General Balcarce", "Sarandí", and three gunboats.
At 3:00 pm the wind again died down, and the action was again reduced to a long range artillery duel. Visibility was steadily reduced by the smoke of the guns, which were audible as far away as Buenos Aires and Colonia del Sacramento. Once again a severe storm rolled in and the fleets struggled fruitlessly to maintain their positions. "General Balcarce" began to settle, but succeeded in remaining afloat. Eventually the storm died down and was replaced by a northeast breeze. Sena Pereira attempted to take advantage of the new wind by retiring to the north to take up better positions.
Once again, the resulting maneuver was poor. "12 de Outubro" could only be saved with the help of the remaining ships, while the hospital ship "Fortuna" was unable to anchor and was blown towards the Argentine lines, where she was captured. As a result of "Fortuna"'s capture John Halstead Coe (comodoro Juan Coe) was freed after having been a prisoner on board since December 1826. It was midnight before the Brazilian squadron was fully reunited in a disorderly anchorage near Sola Island.
Second day.
Exhausted, the Brazilians were not able to lay any plans that night. At dawn, the captains of the fleet boarded "Oriental" to decide the plan of battle; basically, to choose between fighting while maneuvering or to remain anchored. Sena Pereira did not make a decision and opted to choose his tactics as the situation developed.
For his part, Brown was ready. At 8:00 am, with a southeast breeze, he ordered "Sarandí" to run up a red flag, the signal for the Argentines to occupy the windward position, marshal into a battle line, and advance towards the Brazilians.
In response, Sena Pereira gave the order to form a battle line and drop anchor. However, once again, the result was confusion and disorder: some of the gunboat drifted out of formation and downwind. Sena Pereira, shouting ineffectively with a megaphone, tried to restore order. With the Argentines closing quickly and in good order, he changed his decision, now ordering his fleet to raise anchors and attempt to maneuver. "Dona Januária", "Bertioga" and "Oriental" duly advanced on the approaching Argentines, but without the support of the rest of the squadron, which remained dispersed behind them. The three ships were quickly engaged by "General Balcarce" and the Argentine vanguard. The Argentine fire was effective: a shot from "General Balcarce" soon destroyed "Januária"'s bowsprit, and another knocked down her foremast, causing such disruption that she was on the point of foundering. Sena Pereira ordered the small schooner "Vitoria de Colonia" to take "Januária" under tow, but the schooner "Uruguay" blocked the way.
The attack was so rapid and devastating that the captain of "Januária", Lieutenant Pedro Antonio Carvalho, ordered his cannon to concentrate on the Argentine artillery while a team remained to attempt to scuttle the ship and he departed with the crew in boats towards the east.
For his part, Drummond, commander of "Maldonado", attacked "Bertioga", under the command of his old comrade, Lieutenant George Broom. An accurate shot from a heavy Argentine gun knocked down the main mast of "Bertioga" and the ship, now unable to maneuver, was forced to surrender after a half hour of combat.
Throughout this time, "General Balcarce" under Francisco Seguí led a combined attack against "Oriental". The intense crossing fire knocked out "Oriental"'s cannon, half of its carronades, and caused 37 casualties, including Sena Pereira. Despite the losses the Brazilians refused to strike their colors, which had been nailed to the mast. Finally the ship was boarded and Seguí accepted the sword of the