On June 17, 1775 British regulars faced an assemblage of independently minded colonial militia at the Battle of Bunker Hill. By evening of that day the British held the Charlestown peninsula, and a new respect for the determination and resourcefulness of colonial forces. The colonials, if shaken from what was for many the first taste of war (and what it reveals of men's character), had proven to themselves that in direct confrontation they could thwart the British army, a force superior in training, equipment, and organization.
Following the beginning of the war at Lexington and Concord on April 19, 1775 the citizens of Boston found themselves between two armies. General Artemas Ward's New England volunteers surrounded Boston and blockaded the land approaches; General Thomas Gage and 4,600 British soldiers held the city itself. One Bostonian wrote, "We are besieged this moment with 10 or 15,000 men, from Roxbury to Cambridge... We are every hour expecting an attack by land or water."