Thomas Richard Colligan was born in Syracuse, New York on 12 February 1929. Prior to entering the US Navy in August 1950 as a Naval Aviation Cadet, he attended Clarkson College of Technology at Potsdam, New York.
Upon completion of flight training in August 1952 he was commissioned Ensign and received his Naval Aviator wings. Captain Colligan then served with Patrol Squadrons VP-931 and VP-57, completing deployments to the Western Pacific as a Patrol plane commander in P2V ASW aircraft.
From 1956 to 1959 he served as a flight instructor in P2V aircraft at NAS Hutchinson, Kansas and NAS Corpus Christi, Texas. Captain Colligan then served aboard USS Oriskany (CVA 34) as Naval Tactical Data Systems (NTDS) Officer during which time the NTDS Task Group completed the operational evaluation and first deployment o NTDS of Seventh Fleet. He then served two years as Anti-Air Warfare Officer on the Staff of the Commander Sixth Fleet.
In mid-1965 Captain Colligan reported to the pre-commissioning detail and subsequently served as Operations Officer, USS Wainwright (DLG-28). Following a short tour at the US Naval Postgraduate School, Monterey, California, captain Colligan served two years as Operations Officer aboard USS Long Beach (CGN-9).
Captain Colligan commanded USS Mahan (DLG-11) from July 1970 to February 1972 during which time USS Mahan completed seven months of operations in Seventh Fleet. Following this tour, he reported to the Office of the Chief of Naval Operation. In 1973 Captain Colligan attended the Industrial College of the Armed Forces at Fort Lesley J. McNair in Washington, DC. Concurrent with this assignment, he attended George Washington University, from which he received his Master of Science degree in Administration.
Captain Colligan reported to the USS Oklahoma City (CG-5) from assignment as Operations and Plans Officer on the Staff of Commander Cruiser-Destroyer Group Three.