Minute Man National Historical Park preserves the sites where Colonial militia men and British soldiers clashed on April 19, 1775, in the fighting that began the American Revolution. That day, a force of 700 British soldiers left Boston to seize military supplies stockpiled in Concord, but alarm riders alerted the countryside and militia companies from area towns assembled to defend their communities and liberties. After brief battles at Lexington Green and Concord’s North Bridge, fighting intensified along the Battle Road as British troops marched back toward Boston and militia companies poured in. By afternoon, nearly 4,000 Colonists were firing on the British soldiers, and by day’s end the Colonists had surrounded and laid siege to Boston. At the North Bridge, three companies of British Regulars, about 96 men, opened fire on 400 Colonists advancing from the opposite side. Major John Buttrick of Concord then gave the order, “Fire fellow soldiers, for God’s sake fire!” For the first time, Colonists were ordered to fire on the army of their King, and for the first time, they killed British soldiers, an event Ralph Waldo Emerson later immortalized in his 1837 poem The Concord Hymn as “the shot heard round the world.”