The Battles of Lexington and Concord are generally regarded as the opening engagements of the American Revolutionary War.
Fighting began on April 19, 1775, in the Massachusetts towns of Lexington, Concord, Lincoln, and Menotomy, now Arlington. British regulars marched from Boston to seize colonial military supplies at Concord, but local militia mobilized and confronted them along the route.
The first clash occurred at Lexington Green, where British troops and colonial militia exchanged fire. The British reached Concord, but colonial forces resisted at the North Bridge and then harassed the troops during their retreat to Boston. The day produced casualties on both sides and transformed political resistance into open warfare.
The battles did not instantly create an independent United States. The Second Continental Congress still sought a political solution for a time, and the Declaration of Independence came more than a year later. Other major battles followed, including Bunker Hill, Saratoga, and Yorktown.