When word of the bloody encounters at Lexington and Concord reached England, the British government dispatched additional troops to reinforce the garrison in Boston. Those troops arrived in May 1775. Subsequently, on June 14, 1775, the Continental Congress, meeting in Philadelphia, voted to create the Continental Army, which included the militiamen from Massachusetts and surrounding colonies that were laying siege to the British forces in Boston.
On June 16, American soldiers were sent onto the Charlestown Peninsula, north of Boston, to occupy Bunker Hill, but for reasons that are not entirely clear, they constructed their fortifications on neighboring Breed’s Hill. Viewing the new fortifications as a threat to their position in Boston, British commanders launched an attack on Breed’s Hill on June 17.
Following two failed frontal assaults that resulted in heavy losses, the British routed the Americans on a third try, when reinforcements arrived and the Americans ran low on ammunition. After overrunning the fortifications, the British inflicted heavy damages on the Americans as they fled the Charlestown Peninsula. The fighting on the Charlestown Peninsula lasted about two hours and resulted in 1,054 British casualties, compared with 441 American casualties. The American casualties included Joseph Warren, who had played a key role in Massachusetts leading up the war.
Known as the Battle of Bunker Hill — despite the fact that most of the fighting took place on Breed’s Hill — the combat on the Charlestown Peninsula was the first significantly large battle of the Revolutionary War. Although the British were victorious, the Battle of Bunker Hill was a moral victory for Americans throughout the colonies, who now had real evidence that they could not only engage, but inflict heavy casualties on the greatest military force in the world.