From Wikipedia:
The Battle of Bunker Hill took place on June 17, 1775, mostly on and around Breed's Hill, during the Siege of Boston early in the American Revolutionary War. The battle is named after the adjacent Bunker Hill, which was peripherally involved in the battle and was the original objective of both colonial and British troops, and is occasionally referred to as the "Battle of Breed's Hill."
On June 13, 1775, the leaders of the colonial forces besieging Boston learned that the British generals were planning to send troops out from the city to occupy the unoccupied hills surrounding the city. In response to this intelligence, 1,200 colonial troops under the command of William Prescott stealthily occupied Bunker Hill and Breed's Hill, constructed an earthen redoubt on Breed's Hill, and built lightly fortified lines across most of the Charlestown Peninsula.
When the British were alerted to the presence of the new position the next day, they mounted an attack against them. After two assaults on the colonial lines were repulsed with significant British casualties, the British finally captured the positions on the third assault, after the defenders in the redoubt ran out of ammunition. The colonial forces retreated to Cambridge over Bunker Hill, suffering their most significant losses on Bunker Hill.
While the result was a victory for the British, they suffered heavy losses: over 800 wounded and 226 killed, including a notably large number of officers. The battle is seen as an example of a Pyrrhic victory, as while their immediate objective (the capture of Bunker Hill) was achieved, the loss of nearly a third of their forces did not significantly alter the state of siege. Meanwhile, colonial forces were able to retreat and regroup in good order having suffered few casualties. Furthermore, the battle demonstrated that relatively inexperienced colonial forces were willing and able to stand up to regular army troops in a pitched battle.
The British had taken the ground but at a great loss; they suffered 1,054 casualties (226 dead and 828 wounded), with a disproportionate number of these officers. The casualty count was the highest suffered by the British in any single encounter during the entire war.
