Leo Hewlett Thebaud was born in Madison, New Jersey, on 15 February 1890, son of the late Edward Vincent Thebaud and Elizabeth Hewlett (Scudder) Thebaud. He attended Berkeley School in New York City, Hodder School of Stonyhurst College, England, and the Chestnut Hill (Pennsylvania) Academy, before entering the US Naval Academy, Annapolis, Maryland, by appointment from New York in 1909. Graduated and commissioned Ensign in June, 1913, he subsequently attained the flag rank of Rear Admiral to date from 21 June 1942. His transfer to the Retired List of the Navy became effective 1 March 1952 upon reaching the statutory age, when he was promoted in rank to Vice Admiral on the basis of combat awards.
Ordered upon graduation in 1913 to USS Wyoming, he served in junior officer duties in that battleship, and was at Vera Cruz, Mexico, during the occupation of that city in 1914. From November, 1915 he had detached duty in USS Montana for torpedo instruction, and in July, 1916 he rejoined the Wyoming, serving until April, 1917. During the First World War, he commanded USS Paul Jones in the Atlantic. He was awarded the Navy Cross, and cited for "distinguished service...as commanding officer of the USS Paul Jones (old) acting as escort to troop and merchant convoys from Hampton Roads, and in patrolling against enemy submarines from June to October 1918. On the night of 30 June 1918, while under convoy, USS Henderson took fire and it became necessary to transfer the troops on board to another vessel. The Paul Jones transferred the troops in a skillful and gallant manner. Through the zeal and energy of Lieutenant Thebaud, this old destroyer was kept actively on duty."
From December 1918 until August, 1919, he was Executive Office of USS Wickes. Reporting in the New York Shipbuilding Company, Camden, New Jersey, he had duty in connection with fitting out the destroyer Delong. Detached before her commissioning, he was transferred to the newly-commissioned destroyer Dickerson, serving as her Executive Officer until August, 1920. He the assisted in fitting out the Herndon at the Newport News Shipbuilding and Dry Dock Company, and when that destroyer was commissioned on 29 September 1920 he had duty on board until the following February. He commanded USS Bainbridge for four months before being ordered to the Navy Department, Washington, DC, for duty in the Communications Division, Office of the Chief of Naval Operations, where he served until 19 September 1922.
Reporting in the Naval Academy, Annapolis, he served two and a half years as an Instructor in the Department of Seamanship. In March, 1925 he joined the USS Pennsylvania, and in October was transferred to USS Gilmer for duty as Executive Officer, and when detached in March, 1926 he assumed command of USS James K. Paulding. Returning to Washington in January, 1928, he became Executive Officer of the Mayflower, Presidential yacht, based there, serving in that duty until June, 1929. He then returned to the Naval Academy, Executive Department, for a year's duty.
Returning to sea, he served as First Lieutenant of USS Arkansas from June, 1930 to August, 1931, and thereafter as Aide and Flag Secretary on the staff of the Commander, Cruiser Division FOUR, Scouting Force, in USS Northampton, flagship, until May, 1933. He again reported in the Navy Department, and was assigned duty in Europe as Assistant Naval Attaché at the American Embassy, Paris, France; American Embassy, Madrid, Spain; and at the American Legation, Lisbon, Portugal, serving from August, 1933 to September, 1935. He then returned to the Navy Department, Office of the Chief of Naval Operations, for temporary duty, and the following January was assigned duty in Charge of fitting out USS Clark at Bethlehem Shipbuilding Corporation, Quincy, Massachusetts. He commanded that destroyer from her commissioning, 20 May 1936 until June, 1938.
The next two years he served a tour in the Executive Department of the Naval Academy. When detached in July, 1940 he was designated Commander, Destroyer Squadron 27, Patrol Force, US Fleet, in the Atlantic. In November, 1941 he transferred to command of Destroyer Squadron 13, and in March, 1942 reported for duty with Task Force 24. While serving in those duties he also was designated Commander, US Escort Control and Senior Officer Present Afloat, Londonderry, Northern Ireland.
After brief duty in the Navy Department, Bureau of Naval Personnel, on 23 February 1943 he assumed command of USS Boise. "For exceptionally meritorious conduct..." while in command of that cruiser during the period February to September, 1943, he was awarded the Legion of Merit, Gold Star in lieu of a second Legion of Merit, and the Army's Oak Leaf Cluster in lieu of a third Legion of Merit. The citations in part state:
Legion of Merit: "During the amphibious assault on the Island of Sicily...July 10 to 12 July 1943. Carrying out the highly important tasks assigned him; (he)...bombarded enemy shore installations and support the landing and initial advance of our Army troops with devastating effectiveness..."
Oak-Leaf Cluster in lieu of third Legion of Merit: "For...the performance of outstanding services during United States Navy operations in support of the United States Seventh Army from 8 August to 14 August 1943. As commanding officer of the USS Boise, Captain Thebaud played a prominent part in the planning and execution of the amphibious landings behind the enemy lines in Sicily. The direction of supporting naval gunfire and the high order of seamanship displayed (by him) contributed materially to the rapid advance of the Seventh Army along the northern coast of Sicily.
Gold Star in lieu of second Legion of Merit: "...during the amphibious assault on the West Coast of Italy, September 12 to 16, 1943. Proceeding through enemy-mined waters and often under artillery fire and aerial attack, (he) fought his ship gallantly in support of the Allied assault troops, effectively assisting in the maintenance of beachheads against determined counterattacks and contributing materially to the damage inflicted on the enemy which caused his withdrawal to interior positions..."
He also received a Letter of Commendation with Ribbon from the Commander in Chief, US Atlantic Fleet, citing him for "meritorious service as Commander of a unit of ships engaged in escort and convoy "...operations in the Atlantic during the second World War. He operated his ships with skill and efficiency under the hazards of submarine infested waters and adverse weather conditions and thereby contributed materially to the successful convoying of material and men vital to the fighting fronts of Europe..."
After serving briefly in the Bureau of Naval Personnel, Navy Department, he took command of Cruiser Division TEN in the Pacific Fleet, reporting in November, 1943 and serving ten months. For that period, in which he also served as Commander, Support Unit of a fast carrier Task Group in action in the Marianas and Bonin Islands, and during the Battle of the Philippine Sea, he was awarded the Gold Star in lieu of a fourth Legion of Merit with combat distinguishing device, V.
Reporting in September, 1944 in the Navy Department, he had duty as Assistant Chief of Staff to the Commander in Chief, US Fleet, and was later designated Assistant Chief of Staff (Intelligence) and Director of Naval Intelligence. In September, 1945 he was reassigned as Naval Attaché and Naval Attaché for Air, American Embassies, Paris, France, and Brussels, Belgium. In August, 1946 he reported for temporary duty in the Bureau of Naval Personnel, and the next month was assigned as Deputy Naval Inspector General, Navy Department. From April, 1947 he served as Senior Member of the Naval Sentence Review and Clemency Board, and in June he assumed duty as Naval Inspector General, continuing in that assignment until 29 July 1949.
Ordered to the First Naval District, Boston, Massachusetts, he served as Commandant of that district, with additional duty from June, 1950 to August, 1951 as Commander, Naval Base, Newport, Rhode Island. He was serving as Commandant, First Naval District when relieved of active duty and transferred to the Retired List of the Navy, effective 1 March 1952.
In addition to the Navy Cross, the Legion of Merit with two Gold Stars and Oak Leaf Cluster, and the Commendation Ribbon, all with Combat V, Vice Admiral Thebaud has the Mexican Service Medal; the Victory Medal, Destroyer Clasp; the Second Nicaraguan Campaign Medal (USS James K. Paulding); the American Defense Service Medal, Fleet Clasp; the European-African-Middle Eastern Campaign Medal; the Asiatic-Pacific Campaign Medal; the American Campaign Medal; the Philippine Liberation Ribbon; and World War II Victory Medal.
He also has the Legion d'Honneur, Rank of Commander, from the Government of France; the Order of the British Empire, Honorary Commander (Military Division), from the Government of Great Britain, and others.