Hoar attended Boston College High School, then went on to graduate from Tufts University and receive a second lieutenant's commission in the Marine Corps in 1957.

[2] After completing this tour he was assigned to the 31st Marine Amphibious Unit aboard USS Belleau Wood, participating in three deployments in the Indian Ocean.

He returned to Headquarters Marine Corps in June 1990, earning a promotion to lieutenant general while serving there as Deputy Chief of Staff for Plans, Policies and Operations.

He has served as Director of Hawaiian Airlines, as a Fellow of the World Economic Forum, and on the boards of trustees of Suffolk University and the Center for Naval Analyses.

General Hoar drew upon his experience with CENTCOM in the days leading up to the 2003 invasion of Iraq to stress the importance of allied cooperation, notably the ability to base military operations from Saudi Arabia, Jordan and Turkey, as key to success in the region.

[4] A year after the official cessation of hostilities, Hoar continued to maintain that coalition forces did not have enough troops on the ground to accomplish their mission.

[8] On September 7, 2004, Hoar and seven other retired officers wrote an open letter to President Bush expressing their concern over the number of allegations of abuse of prisoners in U.S. military custody.