Herbert Sylvan Ainsworth was born in San Francisco, California, on 2 September 1920, son of Herbert S. and Sally (LeBret) Ainsworth. He attended High School of Commerce and Drew Preparatory School, both in San Francisco, prior to entering the US Naval Academy, Annapolis, Maryland, on appointment from his native state. Graduated with the Class of 1944 on 9 June 1943 (accelerated course due to World War II), he was commissioned Ensign and subsequently advanced in rank to that of Rear Admiral, to date from 1 July 1970.
Following graduation from the Naval Academy in 1943, he reported on board USS Santa Fe and participated in operations at Tarawa, Kwajalein, Marianas, New Guinea and Bougainville. Detached from that cruiser in September 1944, he next had flight training at the Naval Air Station, Pensacola, Florida, and in 1945 was designated Naval Aviator. In April 1946 he joined Patrol Squadron TWENTY-ONE and saw duty in Okinawa, Sasebo, Tokyo, Shanghai, Hong Kong and Tsingtao. From June 1948 to June 1951 he attended a postgraduate course in aeronautical engineering at the Massachusetts Institute of Technology at Cambridge, from which he received the degree of Master of Science.
In July 1951 he reported as Aircraft Assignment Officer on the Staff of Commander Air Force, US Pacific Fleet and in April 1952 was detached for duty as Maintenance Officer with Patrol Squadron SIX. He again joined the staff of Commander Air Force, Pacific Fleet, to serve until June 1954 on the Patrol Squadron Class Desk. Following an assignment, which extended to July 1957, in the Power Plant Division, Bureau of Aeronautics, Navy Department, Washington, DC, he became Operations Officer and SAR Officer at the Naval Air Station, Port Lyautey, French Morocco.
From January 1959 to November 1961 he was Executive Officer and Commanding Officer of Patrol Squadron TWENTY-ONE (original squadron was also VP-21 in 1946), after which he served as Evaluation Officer and Executive Officer of Air Development Squadron ONE. In July 1962 he reported for instruction (Naval Warfare Course) at the Naval War College, Newport, Rhode Island, and while there completed the two weeks Counterinsurgency Course. In 1963 he received the degree of Master of Arts in International Affairs from George Washington University, Washington, DC.
He reported in August 1963 as Plans Officer, Exercise Plans and Analysis Branch, Headquarters, Commander in Chief Allied Forces, Southern Europe and "for meritorious service from August 1963 to August 1965 as Exercise Project Officer in the Organization and Training Division, Headquarters, Allied Forces, Southern Europe, Naples, Italy..."was awarded the Navy Commendation Medal. The citation further states in part:
"...Captain Ainsworth was assigned complete responsibility for the planning and direction of FALLEX 64, and assisted in the final preparation of SOUTHEX 63, two major NATO multinational exercises conducted in the Southern Region...As a result of the many lessons learned from the exercises, staffs at all levels were able to strengthen and increase the reaction capability of assigned forces and further enhance the unity of effort and solidarity of the southern flank of NATO..."
During the period August to September 1965, he had training at the Naval Amphibious School, Coronado, California, after which he commanded USS Matthews (AKA -90); which operated in the Vietnam area of hostilities. In November 1966 he reported as Commander Fleet Air Wing EIGHT and Commander Task Group, SEVENTY-TWO Point THREE. He was awarded a Gold Star in lieu of the Second Navy Commendation Medal with the following citation:
"For meritorious service while serving as Commander Fleet Air Wing EIGHT and Commander Philippine Air Patrol Group from February 9 to August 4, 1967 during combat operations against the enemy...Captain Ainsworth developed a new concept which greatly improved the overall effectiveness of Market Time Surveillance operations..." The accomplishment of the extremely important and demanding missions of Market Time, Yankee Team, and the "Chieu Hoi” (open arms) Program by Air Patrol units, under the most difficult conditions, was a tribute to his organizational and leadership ability..."
From December 1967 to January 1970 he served as Assistant Director of the Program Appraisal Division, Office of Program Appraisal, Navy Department, Washington, DC, after which he was assigned as Assistant Chief of Staff for Logistics to the Commander in Chief Allied Forces, Southern Europe. He was awarded the Legion of Merit and cited in part as follows: "...In this capacity...his personal direction and expert guidance were instrumental in the strengthening of forwarded defenses in Hellenic and Turkish Thrace and in the multifunctional expansion of maritime airfields in the Mediterranean region..." He reported in November 1972 as Commander Fleet Air Wings, US Pacific Fleet/Commander Fleet Air, Moffett, with headquarters at the Naval Air Station, Moffett Field, California. Upon the disestablishment of the Fleet Air activities on 1 July 1973, his title was changed to Commander Patrol Wings, US Pacific Fleet. He served as such until relieved of active duty pending his retirement effective 1 July 1974.
In addition to the Legion of Merit and the Navy Commendation Medal with Gold Star, Rear Admiral Ainsworth had the American Defense Service Medal; American Campaign Medal; Asiatic-Pacific Campaign Medal; World War II Victory Medal; China Service Medal; Navy Occupation Service Medal, Asia Clasp; National Defense Service Medal with bronze star and the Vietnam Service Medal with four stars. He also had the Republic of Vietnam Campaign Medal with Device and the Republic of Vietnam Armed Forces Meritorious Unit Citation (Gallantry Cross).
Rear Admiral Ainsworth was a member of Sigma Xi Engineering Society.