The night of April 18-19, 1775, Paul Revere along with William Dawes and Samuel Prescott rode along the routes between Boston and Concord warning the citizens that the British were marching on Concord. Though the plans had been discovered 2 days earlier, it was not known when the British would depart, or by what route.
Minutemen was a name given to those who responded to the warnings Revere, Dawes, and Prescott delivered. They were so named, because they responded with "a minute's notice."
At dawn, April 19, 1775 the British force arrived in Lexington, and were confronted by a small force of Minutemen. Both sides were under orders "do not fire until fired upon," but when a shot rang out, both sides assumed they had been fired upon, and the Revolutionary War had begun. The Minutemen were dispersed at Lexington but another force successfully held the bridge at Concord and then Minutemen from both forces harried the British column all the way back to Boston with frequent "Sniper" style attacks from the forest and stone walls lining the road.