"About 5 a.m. on April 19, 700 British troops under Major John Pitcairn arrived at the town to find a 77-man-strong colonial militia under Captain John Parker waiting for them on Lexington’s common green. Pitcairn ordered the outnumbered Patriots to disperse, and after a moment’s hesitation, the Americans began to drift off the green. Suddenly,the “shot heard around the world”was fired from an undetermined gun, and a cloud of musket smoke soon covered the green. When the brief Battle of Lexington ended, a handful of Americans lay dead and several others wounded. The American Revolution had begun."
https://www.history.com/this-day-in-history/revere-and-dawes-warn-of-british-attack