You’re confusing causes of the war vs the start of the war. Two different things. On the night of April 18, 1775, hundreds of British troops marched from Boston to nearby Concord, Massachusetts in order to SEIZE AN ARMS CACHE. Paul Revere and other riders sounded the alarm, and colonial militiamen began mobilizing to intercept the Redcoats. On April 19, local militiamen clashed with British soldiers in the Battles of Lexington and Concord in Massachusetts, marking the “shot heard round the world” that signified the start of the Revolutionary War.