What was the name of the first major military action of the American Revolutionary War?

The Battles of Lexington and Concord were the first major military actions of the American Revolutionary War.

They took place on April 19, 1775, in Massachusetts. British regulars marched from Boston toward Concord to seize colonial military supplies, while Patriot riders warned local militias of the expedition. Fighting began at Lexington and continued through Concord and along the British retreat toward Boston.

The clashes were not a single engagement but a day-long series of encounters. Patriot forces suffered casualties, yet the British expedition failed to destroy the supplies and returned to Boston under sustained attack. The fighting began the Siege of Boston and turned political resistance into open war. The Battle of Bunker Hill followed in June 1775, but Lexington and Concord came first.