The first major military engagements of the American Revolutionary War at Lexington and Concord took place on April 19, 1775.
British troops marched from Boston to Concord to seize colonial military supplies. Patriot riders, including Paul Revere, William Dawes, and Samuel Prescott, had warned local communities, allowing militia units to assemble at Lexington and later at Concord's North Bridge.
The fighting began at Lexington, where the first exchange was a brief skirmish. The British then continued toward Concord, but militia resistance forced them to retreat toward Boston. Patriot forces pursued the column and inflicted substantial casualties along the road.
The phrase “shot heard round the world” is associated with the opening of the conflict, although the identity of the person who fired the first shot remains disputed. The battles launched the armed phase of the Revolution, before the Declaration was written.