A force of militiamen under Col. Prescott were sent by the Committee of Safety to occupy and fortify Bunker Hill, on the Charlestown Heights, overlooking the besieged Boston. They arrived, and threw up a fort, but not on Bunker Hill, but on the closer, but lower Breeds Hill.

General Gage, the following dawn, had the navy fire on the positions, and launched an amphibious attack under generals Howe and Pigot. Attempts to outflank the Americans failed, so the British resorted to frontal attacks, the first two of which were beaten back for great loss. On the third attempt the defenders ammunition began to run out, and the British bayonet charge reached the barricades. As the Americans were forced to fall back many were killed and wounded in a disorganised withdrawal. The heavy casualties suffered by the British regulars, however, gave heart and confidence to the fledgling American continental army.