US Navy admiral, ambassador (1875–1959)
William Daniel Leahy () (6 May 1875 – 20 July 1959) was an American naval officer. The most senior United States military officer on active duty during World War II, he held several titles and exercised considerable influence over foreign and military policy. As a fleet admiral, he was the first flag officer ever to hold a five-star rank in the U.S. Armed Forces.
An 1897 graduate of Annapolis, Leahy saw active service in the Spanish–American War, the Philippine–American War, the Boxer Rebellion in China, the Banana Wars in Central America, and World War I. He was the first member of his cadet class to reach flag rank, as the Chief of the Bureau of Ordnance from 1927 to 1931. He subsequently served as Chief of the Bureau of Navigation from 1933 to 1936, and commanded the Battle Fleet from 1936 to 1937. As Chief of Naval Operations from 1937 to 1939, he was the senior officer in the United States Navy, overseeing the expansion of the fleet and preparations for war.
After retiring from the Navy, Leahy was appointed the governor of Puerto Rico in 1939 by President Franklin D. Roosevelt. In his most controversial role, he served as the Ambassador to France from 1940 to 1942. American policy was aimed at keeping the government of Vichy France free of German control, but Leahy had limited success. He came to believe that the United States should back Free France instead of Vichy France, and asked to be recalled after the Japanese attack on Pearl Harbor brought the United States into the war.
Leahy was recalled to active duty as the Chief of Staff to the President in 1942 and served in that position for the rest of the war. He was the highest-ranking active-duty member of the military. As the "de facto" first Chairman of the Joint Chiefs of Staff, he oversaw all of the American armed forces. He also presided over the American delegation to the Combined Chiefs of Staff. He was a major decision-maker during the war and was second only to the President in authority and influence. Leahy was promoted to five-star rank in December 1944. He served Roosevelt's successor Harry S. Truman, helping shape postwar foreign policy until he retired in 1949. Although he did not oppose the use of the nuclear weapons during the war, in the post-war period he rejected war plans that placed too much emphasis on the first use of nuclear weapons.
Early life and education.
William Daniel Leahy was born in Hampton, Iowa, on 6 May 1875, the first of seven children of Michael Anthony Leahy, a lawyer and American Civil War veteran, who was elected to the Iowa Legislature in 1872, and his wife Rose Mary née Hamilton. Both parents were born in the United States but his grandparents were immigrants from Ireland. He had five brothers and a sister. His father was re-elected in 1874, but moved to Wausau, Wisconsin, in 1882. In 1889, the family moved again, this time to Ashland, Wisconsin, where Leahy attended high school. His nose was broken in an American football match and his family lacked the money to get it fixed, so it remained crooked for the rest of his life.
Leahy wanted to attend the United States Military Academy at West Point, New York, but this required a Congressional appointment, and Leahy was unable to secure one. His local congressman, Thomas Lynch, offered Leahy an appointment to the United States Naval Academy in Annapolis, Maryland, which was much less popular among boys in the landlocked Midwestern United States. Leahy passed the entrance examinations and was admitted as a naval cadet in May 1893. 
Leahy learned how to sail on the on a summer cruise to Europe, although the vessel only made it as far as the Azores before breaking down. He graduated 35th out of 47 in the class of 1897. His class was the most successful ever: five of its members would reach four-star rank while on active duty: Leahy, Thomas C. Hart, Arthur J. Hepburn, Orin G. Murfin and Harry E. Yarnell. As of 2022[ [update]], no other class has had more than four.
Naval service.
Spanish-American War.
Until 1912, naval cadets graduating from Annapolis had to complete two years' duty at sea and pass examinations before they could be commissioned as ensigns. Leahy was assigned to the battleship , which was then at Vancouver, British Columbia, for celebrations of Queen Victoria's Diamond Jubilee. He was on board when she made a dash through the Strait of Magellan, and around South America in the spring of 1898 to participate in the Spanish–American War. The "Oregon" took part in the blockade and bombardment of Santiago and shelled the small town of Guantánamo, which Leahy felt was "unnecessary and cruel". In the Battle of Santiago on 3 July, Leahy was in command of the ship's forward turret. This was the only naval battle Leahy witnessed in person.
Seeking further action, Leahy volunteered to serve on the gunboat , which was bound for the war in the Pacific, traveling via the Mediterranean Sea and the Suez Canal, but he got only as far as Ceylon when he received orders to report to Annapolis for his final ensign's examinations. He was therefore left behind, and had to return to the United States on the . He reached Annapolis in June 1899. He passed his examinations, and was commissioned as an ensign on 1 July 1899. After few weeks' leave, spent with his parents in Wisconsin, and a few months' service on the cruiser at the Mare Island Navy Yard, he joined the monitor on 12 October 1899. A week later it set sail for the Philippines. It arrived in Manila on 24 November, and Leahy rejoined the crew of the "Castine" five days later.
China and Philippine–American Wars.
On 17 December 1899, "Castine" sailed for Nagasaki, but it developed engine trouble on 12 February 1900 and stopped in Shanghai to make repairs. While it was there the Boxer Rebellion broke out in China, and it was retained in Shanghai to help British, French and Japanese forces guard the city, although Leahy did not like their chances if the 4,500 Chinese troops in the vicinity joined the uprising, as they had in the Battle of Tientsin. On 28 August, the "Castine" was ordered to Amoy help protect American interests there against the possibility of a Japanese coup. After the threat had passed, the "Castine" returned to the Philippines, arriving back in Manila on 16 September 1900.
The Philippine–American War was still ongoing, and the "Castine" supported American operations on Marinduque and Iloilo. Leahy was appalled by American brutality and the widespread use of torture. Still an ensign, he was given his first command, the gunboat , a refitted ex-Spanish vessel. It had a crew of 23. His period in command ended when the "Mariveles" lost one of its propellers and had to be laid up for repairs. He was then reassigned to the , a stores ship which was engaged in bringing supplies from Australia to the Philippines. While in the Philippines he passed the examinations required for promotion to lieutenant, junior grade, and was promoted to that rank on 1 July 1902. He made his final trip to the Philippines in September 1902, and returned to the United States later that year.
Sea duty alternated with duty ashore. Leahy was assigned to the training ship in San Francisco, where he was promoted to lieutenant on 31 December 1903. He met and courted Louise Tennent Harrington. Leahy married Louise on 3 February 1904. Louise subsequently convinced him to convert to Episcopalianism.
Leahy helped commission the cruiser but swapped assignments with an officer on the so that he could remain in San Francisco with Louise, who was pregnant. Over the next two years the "Boston" cruised back and forth between San Francisco and Panama, where the Panama Canal was under construction. He was in Acapulco when their son and only child, William Harrington Leahy, was born on 27 October 1904, and did not see his son until five months later. He was present for the 1906 San Francisco earthquake. His family had to leave their house in the face of the resulting fires. It survived undamaged, although they had to live in a hotel for several months before they could return.
On 22 February 1907, Leahy returned to Annapolis as instructor in the department of physics and chemistry. He also coached the academy rifle team. After two years ashore, he received orders on 14 August 1909, to return to San Francisco and sea duty as navigator of the armored cruiser , commanded by Captain Henry T. Mayo, in whom Leahy found a patron and a role model. In September, the "California" was one of eight ships that paid an official visit to Japan, where Leahy saw Admiral Heihachirō Tōgō. Mayo switched Leahy's assignment from navigator to gunnery officer.
Leahy was promoted to lieutenant commander on 15 September 1909, and in January 1911, the commander-in-chief of the Pacific Fleet, Rear Admiral Chauncey Thomas Jr., chose him as his fleet gunnery officer. In October, the "California" returned to San Francisco for a fleet review in honor of President William Howard Taft, and Leahy served as Taft's temporary naval aide for four days.
Banana Wars.
Rear Admiral William H. H. Southerland succeeded Thomas as commander of the Pacific Fleet on 21 April 1912. The "California" sailed to Manila and then to Japan before returning to San Francisco on 15 August. A few weeks later, Southerland received orders to proceed to Nicaragua and be prepared to deploy a landing force for the United States occupation of Nicaragua. Along with his duties as gunnery officer, Leahy became the chief of staff of the expeditionary force and the commander of the small garrison at Corinto, Nicaragua. He came under fire while repeatedly escorting reinforcements and supplies over the railroad line to León. Privately, he thought that the United States was backing the wrong side, propping up a conservative elite who were exploiting the Nicaraguan people.
In October 1912, Leahy came ashore in Washington, D.C., as assistant director of gunnery exercises and engineering competitions. Then, in 1913, Mayo had him assigned to the Bureau of Navigation as a detail officer. Mayo and then his replacement, Rear Admiral William Fullam, were reassigned, leaving Leahy as the acting chief of the bureau. It was one of the Navy's most sensitive offices, as it controlled officer assignments. Leahy's wife Louise enjoyed the social milieu of Washington, and socialized with Addie Daniels, the wife of Josephus Daniels, the Secretary of the Navy. Leahy established a close friendship with the Assistant Secretary of the Navy, Franklin D. Roosevelt. 
As Leahy's three-year tour of shore duty approached its end in 1915, he hoped to command the new destroyer tender but Daniels had the assignment changed to command of the Secretary of the Navy's dispatch gunboat, the . Leahy assumed command of the "Dolphin" on 18 September 1915. The ship took part in the United States occupation of Haiti, where Leahy again acted as chief of staff, this time to Rear Admiral William B. Caperton. In May 1916, "Dolphin" participated in the occupation of the Dominican Republic too. During the summer, Roosevelt used it as his family yacht, cruising down the Hudson River from the Roosevelt family estate in Hyde Park, New York, and along the coast to his holiday house on Campobello Island. Leahy was promoted to commander on 29 August 1916.
World War I.
Following the United States entry into World War I In April 1917, "Dolphin" was sent to the United States Virgin Islands to assert America's control there. There was a rumor that a Danish-flagged freighter in the vicinity, the "Nordskov", was a German merchant raider in disguise, and "Dolphin" was sent to investigate. If it had been, Leahy would have been outgunned, but an inspection determined that the rumors were false. In July 1917, Leahy became the executive officer of . It was the Navy's newest battleship, but it was not sent to Europe due to teething troubles with its new design and a shortage of fuel oil in Britain.
In April 1918 Leahy assumed command of a troop transport, the . Shortly before it was due to depart for France, Leahy was summoned to Washington, D.C., by the Chief of