Leonidas Dixon Coates was born on October 24, 1907, in Fresno, California, son of Mrs. Beatrice Williams Coates and the late Mr. Leonidas D. Coates. He was graduated from Polytechnic High School in Oakland, California, in June 1925, and on June 16, 1926 entered the US Naval Academy, Annapolis, Maryland Ensign on June 5, 1930, and through subsequent promotions attained the rank of Rear Admiral to date from August 1, 1956.
Following graduation from the Naval Academy in June 1930, he was assigned to the USS New York, in which he served for a year. He continued sea duty successively in the USS Texas, USS Pennsylvania, and USS Saratoga until April 1933, when he was ordered to the Naval Air Station, Pensacola, Florida, for flight training. Completing the course, he was designated Naval Aviator on March 26, 1934, and in June of that year reported to the USS Houston for duty with Scouting Squadron Ten-S.
He returned to Annapolis as a student at the Postgraduate School from June 1936 to June 1938 and, continuing the course at the California Institute of Technology, he received the degree of Master of Science in Aeronautical Engineering in June 1939. He then had duty, for a year each, with Fighting Squadron Three, based on the USS Saratoga, and Patrol Squadron Seventy-Four at Norfolk, Virginia. In June 1941 he was designated for Engineering Duty (Aeronautical), and was detached from Patrol Squadron Seventy-Four in October of that year.
He was serving on the Patrol Plane Design Section of the Bureau of Aeronautics when the United States entered World War II in December 1941, became Head of the Section, and conintued duty there throughout the war and until August 1946, when he was made Bureau of Aeronautics Representative for Douglas Aircraft Company, Inc., El Segundo, California. In May 1947 he reported for duty as Aircraft Material Officer on the staff of Commander Air Force, Pacific Fleet, with Headquarters at the Naval Air Station, Pearl Harbor, Territory of Hawaii.
On May 18, 1949 he was again ordered to the Bureau of Aeronautics, this time for duty as Deputy Director of the Aircraft Division. In September 1950 he was sent to Harvard University for the Advanced Management Program, and on completion of the course returned to the Bureau of Aeronautics to serve as Director of the Guided Missiles Division until June 1951, when he became Deputy Assistant Chief for Research and Development. Under orders of July 9, 1952, he was detached to the Naval Air Station, Jacksonville, Florida where he served for two years as Overhaul and Repair Officer. In August 1954 he was assigned duty as Deputy and Assistant Chief of Naval Research, Navy Department.
In March 1956 he reported as Force Maintenance and Material Officer on the staff of Commander Air Force, US Atlantic Fleet, and in June 1957 became Assistant Chief of the Bureau of Aeronautics (Research and Development), Navy Department. In August 1959 he was designated Deputy Chief of that Bureau and served in that capacity until December 1959. He was then transferred to the Office of the Chief of Naval Operations, Navy Department, for duty as Director of Development Planning. Having been appointed Chief of Naval Research by the President, he assumed the duties of that Office on February 1, 1961. “For exceptionally meritorious conduct… during the period June 1961 to June 1964 as Chief of Naval Research…” he was awarded the Legion of Merit. The citation further states:
“During this period by dynamic evolution of Naval ships, aircraft, associated equipment and technology, Rear Admiral Coates has made major contributions to the scientific and engineering achievements of the Office of Naval Research. Exercising outstanding professional skill and resourcefulness, he has insured the maximum scientific and technological advancement of the Navy, and has been responsible for a high order of enthusiasm and morals among personnel of the offices and laboratories under his cognizance. In addition he had insured the most effective utilizations of limited resources of men and money…”
On July 1, 1964 he was transferred to the Retired List of the US Navy.
In addition to the Legion of Merit, Rear Admiral Coats has the American Defense Service Medal with bronze “A”; American Campaign Medal; World War II Victory Medal and the National Defense Service Medal.