The main British Garrison was based at Boston Massachusetts. Earlier that year a number of marines under the command of Major John Pitcairn had reinforced the garrison who were finding it difficult to maintain law and order amongst the population, who were wanting independence from Great Britain.
In April, the British Commander Lt Gen the Hon Thomas Cage received information American rebels has amassed powder, arms and ammunition in the town of Concord, which is north of Boston. He dispatched a force of 800 to destroy the illegal arsenal, but the rebels were forewarned by one Paul Revere who rode through the night shouting "The British are coming".
As the British, at daybreak, approached Lexington, they were confronted by a force of armed Minutemen assembled on the village green and barring their progress. Major Pitcairn, leading the advance, demanded that the rebels throw down their arms and disperse. As the Minutemen reluctantly give was a shot rang out from behind a stone wall, wounding a British soldier. The troops returned fire and eight minutemen were killed and the rest fled. The British marched on to Concord and carried out their mission. On their return to Boston they were picked off by American sharpshooters, hiding behind rocks, trees and bushes.
On May 24th over 700 Marines disembarked at Boston enabling the marine force to form two battalions. The 1st Battalion was commanded by Major James Short and the 2nd Battalion was commanded by Major John Tupper with Major John Pitcairn in overall command.
Two strategic positions overlooking Boston, Bunker Hill and Breed's Hill were occupied by the rebels who had dug in. Instead of cutting off the peninsula and advancing from the mainland Cage sent 2,200 men including both Marine Battalions,to capture the positions in a frontal assault from the sea. They launched three attacks on the American positions before they were chased off at bayonet point. Heavy casualties were taken by the British, this included Major John Pitcairn who died in the arms of his son, also a Marine, who carried him of the field on his shoulders
The British presence in Boston was now untenable and the city was evacuated in 1776. The Marines sailed for Halifax, Nova Scotia where they remained for the next two years. The Grenadier companies were later detached and served in New York and Pennsylvania, and the fleet Marines fought at sea and on land at Savannah and Charleston, the Corps took no major part in the rest of the American Revolutionary War,