Thomas Gage began a British military career in Europe before gaining extensive experience in North America during the Seven Years' War. He served in Edward Braddock's expedition and was wounded in the defeat near the Monongahela in 1755. Later responsibilities included organizing light infantry and participating in the campaigns that established British control over French Canada. He served as military governor at Montreal before becoming commander in chief of British forces in North America in 1763.

Gage's command faced the resistance associated with Pontiac's War and the difficulties of maintaining an expanded frontier empire. He coordinated garrisons, communications, and military policy over a large territory. As conflict over parliamentary taxation developed, troops became involved in enforcing imperial authority. The deployment to Boston in 1768 placed soldiers within a hostile political environment, and the Boston Massacre in 1770 further damaged relations between the army and colonial residents.

In 1774 Gage became governor of Massachusetts while retaining military command. He was charged with implementing measures imposed after the Boston Tea Party, including changes to the colony's government and restrictions on the port. Efforts to disarm resistance by seizing powder and military supplies met organized colonial opposition. In April 1775 he sent regular troops toward Concord to search for stores. Fighting at Lexington and Concord and along the return route began open war, leaving British forces confined increasingly to Boston.

Gage directed the defense of the city during the early siege. The British assault on the American positions at Bunker Hill in June 1775 gained the ground but suffered severe casualties, revealing the strength of colonial resistance. He issued proclamations seeking to suppress rebellion, yet negotiations and coercion had failed to restore ordinary government. Recalled to Britain later that year, he was replaced by William Howe and did not return to command in America. He subsequently received promotion to full general and died in 1787. His career reflects the transition from military management of a growing empire to armed confrontation with its own colonies. Long familiarity with America did not provide an effective solution to a crisis rooted in political authority and consent, and his attempts to apply military enforcement helped produce the war the government had hoped to prevent.