Joe McKnitt Alexander was born in Huntersville, North Carolina, on 16 September 1911, son of J. D. and Carolyn (Woodside) Alexander. He was graduated from Huntersville High School and attended the University of North Carolina, at Chapel Hill, for a year before his appointment to the US Naval Academy from the Ninth District of North Carolina in 1930. He was graduated and commissioned Ensign in the US Navy on 31 May 1934, and through subsequent promotions attained the rank of Commander, to date from 1 February 1944.
Upon graduation from the Naval Academy he was assigned to USS Raleigh, in which he served as a junior officer until November 1937. He had brief duty aboard USS Kane, and from December 1937 until June 1938 was under instruction in submarines at the Submarine Base, New London, Connecticut. Qualifying for submarine duty, he was assigned first to USS R-14, then after assisting in the fitting out of USS Spearfish at the Electric Boat Company, Groton, Connecticut, served in that submarine from her commissioning in July 1939 until July 1940.
When detached from the Spearfish, he joined USS Richmond, and served in that cruiser before and following the United States' entry into World War II in December 1941 until December 1943, being her First Lieutenant and Damage Control Officer during the last six months of that period. He returned to Annapolis as Instructor in the Department of Electrical Engineering and Physics, from February 1944 to June 1945, after which he reported to the New York Shipbuilding and Dry Dock Company, New York, New York, to assist in fitting out USS Macon.
He joined Macon at her commissioning on 26 August 1945, and served as her First Lieutenant and Damage Control Officer until March 1946, and as Navigator for the fifteen months to follow. In June 1947 he assumed command of USS Zellars, and remained in that command until March 1949. He was then ordered to Key West, Florida, where he was a member of the staff of Commander Naval Base, until July 1950.
Assigned next to the Military Sea Transportation Service, Western Pacific, he reported to the Commander at Headquarters in Tokyo, Japan, on 28 August 1950, and served at that Headquarters until January 1951, when he was assigned as MSTS Representative, Naval Control of Shipping Officer, Okinawa, until October 1951. He then returned to duty with the MSTS Western Pacific Headquarters in Tokyo and Yokahama, Japan, from 21 October 1951 until 19 March 1953, when he was detached to return to the United States.
On 10 May 1953 he took command of USS Guadalupe (AO 32). He was detached on 17 July 1954, and on 20 August reported to Headquarters, Sixth Naval District, Charleston, SC, where he had duty as Assistant Reserve Coordinator for that district.
Commander Alexander had the American Defense Service Medal, Fleet Clasp; Asiatic-Pacific Campaign Medal; American Campaign Medal; World War II Victory Medal; Navy Occupation Service Medal; China Service Medal; National Defense Service Medal; Korean Service Medal; and the United Nations Service Medal.