The Battles of Lexington and Concord began on April 19, 1775.
British troops marched from Boston toward Concord to seize colonial military supplies. Patriot riders, including Paul Revere, William Dawes, and Samuel Prescott, warned local militias that the expedition was approaching. Fighting began at Lexington Green, where Massachusetts militia faced British regulars.
The British continued to Concord, where colonists confronted them at the North Bridge. The troops then withdrew toward Boston under sustained militia fire. The day marked the first major military actions of the American Revolutionary War.
A common mix-up is placing the start of the Revolution at the Boston Massacre in 1770 or the Battle of Bunker Hill in June 1775. Those events were important, but Lexington and Concord came first. The clashes helped transform a political dispute into an armed rebellion and led to the Siege of Boston.