Rear Adm. Hennegan is a 1980 graduate of the United States Naval Academy and a native of New London, Connecticut.
A submariner, his tours at sea include assignments in USS Haddock (SSN 621), USS James Madison (SSBN 627), and USS Grayling (SSN 646). Hennegan commanded USS Buffalo (SSN 715) and Submarine Squadrons Six and Eight.
Ashore, he served on the staffs of the secretary of defense, the chief of naval operations, and the director, Naval Nuclear Propulsion. He served in fleet support positions on the staff of Commander, Submarine Force, U.S. Pacific Fleet and at Submarine Squadron 16. He also served as the deputy chief of Legislative Affairs for the Navy, on the Department of Defense Transition Task Force in the Office of the Secretary of Defense, and as the deputy commander, Joint Functional Component Command for Global Strike at U.S. Strategic Command. He most recently served as commander, Submarine Group Nine.
Hennegan completed studies in the Navy’s Nuclear Propulsion Program. He earned a Master of Science degree in Operations Research from the Naval Postgraduate School, completed the Harvard Business School Advanced Management Program, the National Securities Studies Program at George Washington University, and the Seminar XXI Program at the Massachusetts Institute of Technology.
His awards include the Defense Superior Service Medal, the Legion of Merit, and the Vice Admiral Stockdale Award for Inspirational Leadership.