John Cadwalader was born in Philadelphia, Pennsylvania, on January 9, 1910, on of Mrs. John (Margaret Nicoll) Cadwalader and the late Mr. Cadwalader. He attended the University of Pennsylania, at Philadelphia, where he was a member of the Varsity Crew (1931), and Delta Phi and Phi Beta Kappa fraternities, and after graduation remained to serve as a instructor from 1934 until 1940. He holds the degrees of Bachelor of Arts, Master of Arts, and Doctor of Philosophy from that University.
He was an enlisted memmber of the Pennsylvania National Guard (Cavalrytrooper) during the period June 1932 through 1940, and on March 13, 1941 began his Naval Service in the rank of Lieutenant (jg), US Naval Reserve. Through normal promotions, he attained the rank of Captain, to date from July 1, 1956.
Called to active duty in May 1941, he served until February 1942 as an instructor at the US Naval Academy, Annapolis, Maryland, being there when the United states entered World War II, December 8, 1941. In March 1942 he joined the USS Washington (BB-56), and was Assistant Navigator of that battleship during the period when she operated with the British Home Fleet in the North Atlantic and later when she sank a Japanese battleship during the Guadalcanal Campaign in the Pacific. Detached from the Washington in April 1943, he reported as Gunnery Officer of the USS Monterey (CVL 26), in May. As such, he participated in action in the Central and Western Pacific, including the Gilberts, Marshalls and Marianas operations; the Bismarck-Archipelago operation; Asiatic-Pacific raids; Hollandia operation; action in the Western Caroline Islands and New Guinea; Leyte and Okinawa Gunto operations; and the THIRD Fleet operation against Japan.
From July to November 1945 he was assigned to the pre-commissioning detail of the USS Franklin D. Roosevelt (CVB-42), at the New York Navy Yard, after which he was released to inactive duty status. In June 1946 he was recalled to active duty, and during the next four years was assigned to Training and Administration, Naval Reserve, in the Fourth Naval District. From July to December 1950 he was Officer in Charge of the Naval Training Publication Center, Potomac River Naval Command, Washington, DC. Throughout 1951 he was a Military Observer with the United Nations Military Observer Group in Kashmir.
In February 1952 he joined the USS Marquette (AKA95), as Executive Officer, and during his period of service in that capacity the Marquette operated with the SIXTH Fleet in the Mediterranean for six months. He was detached from the Marquette in July 1953 and a month later reported to Headquarters, Thirteenth Naval District, Seattle, Washington, where he served as District Security Officer, District Operations (temporary additional duty), and Assistant to the Director of Training. In September 1955 he was assigned to Task Force 43, for Operation Deep Freeze, as Operations Officer, US Naval Support Force, Antartica.
Captain Cadwalader has the American Defense Service Medal; the European-African-Middle Eastern Campaign Medal with one bronze engagement star; the Asiatic-Pacific Campaign Medal with threee silver stars (15 engagement); the World War II Victory Medal; the Navy Occupation Service Medal, Asia Clasp; the National Defense Service Medal; and the Philippine Liberation Ribbon with two stars.