Jack Agnew was born in Bonham, Texas, on 5 September 1909, son of Mrs. Jenny Agnew (nee Mildred Jane Roberts) and the late Ed J. Agnew. He was graduated from Bonham High School in 1926, and in June of that year entered the US Naval Academy, Annapolis, Maryland, with the Class of 1930. Graduated and commissioned Ensign on 5 June 1930, he transferred from the Line of the Navy to the Supply Corps in the rank of Lieutenant (jg) in 1935, and subsequently attained the rank of Commander to date from 15 October 1942.
After graduation from the Naval Academy in June 1930, he served for several months each in the battleships Mississippi and Idaho, units of Battleship Division 4, Battle Fleet, and USS California, flagship of Commander, Battle Fleet. From July 1932 until April 1931 he was aboard USS Hannibal on survey in Central American waters, and for fifteen months thereafter served in USS Portland, a unit of Cruiser Division Six, Scouting Force.
He attended Finance and Supply School, in Philadelphia, Pennsylvania, from the time of his transfer to the Supply Corps in 1935 until June 1936, and for the next year served as Disbursing Officer for the Naval Hospital and Officer in Charge of the Commissary Store at Pearl Harbor, TH. In October 1937 he was transferred to duty as Disbursing Officer of the Submarine Base at Pearl Harbor, and served in that capacity until detached to return to the United States in June 1938.
Duty from July 1938 until September 1939 as Assistant to the Supply Officer of the Norfolk Navy Yard, Portsmouth, Virginia, was followed by further sea duty in USS Patoka, operating off Norfolk, Virginia. At the time of the Japanese attack on Pearl Harbor, 7 December 1941, he had been aboard USS Alcor, destroyer tender, for six months. He continued to serve in that vessel until September 1942, and a month later reported for duty as Supply Officer of the Naval Air Station, Patuxent River, Maryland.
While he was aboard USS Wasp from March 1944 until May 1945, that carrier participated in the raid on Marcus Island; the capture, occupation and defense of Saipan, Tinian, and Guam; the Philippines, Iwo Jima and Okinawa operations. He received a Letter of Commendation with Ribbon and Combat "V," from the Commander in Chief, Pacific Fleet, for "meritorious service in the performance of his duties as Supply Officer aboard the US aircraft carrier Wasp during prolonged operations against the enemy from March 1944 to May 1945...." He was also entitled to the Ribbon for, and a facsimile of, the Navy Unit Commendation awarded the USS Wasp for distinguished service during that period.
In June 1945 he reported to the Naval Air Station, San Diego, California, and detached a year later, he was designated Officer in Charge of the Naval Storehouse, Gulfport, Mississippi where he remained until February 1947. Thereafter until July 1949 he served successively as Assistant Fleet Supply Officer on the staff of Commander Service Force, Atlantic Fleet; and as Logistics Officer on the staff of Commander in Chief, US Atlantic Fleet.
A logistics student at the Naval War College, Newport, Rhode Island, from August 1949 until June 1950, Commander Agnew was Officer in Charge of the Navy Regional Accounts Office, Philadelphia, Pennsylvania.
In addition to the Commendation Ribbon with Combat "V," and the Navy Unit Commendation Ribbon (USS Wasp), Commander Agnew had the American Defense Service Medal with star; the American Campaign Medal; the Asiatic-Pacific Campaign Medal with one silver, two bronze stars (seven engagements); the World War II Victory Medal; and the Philippine liberation Ribbon with two stars.