During the American War for Independence, British forces are forced to evacuate Boston following Patriot General George Washington's successful placement of fortifications and cannons on Dorchester Heights, which overlooks the city from the south.
During the evening of March 4, Patriot General John Thomas, under orders from Washington, secretly led a force of 800 soldiers and 1,200 workers to Dorchester Heights and began fortifying the area. To cover the sound of the construction, Patriot cannons, besieging Boston from another location, began a noisy bombardment of the outskirts of the city. By the morning, more than a dozen cannons from Fort Ticonderoga had been brought within the Dorchester Heights fortifications. British General Sir William Howe hoped to use British ships in Boston Harbor to destroy the Patriot position, but a storm set in, giving the Patriots ample time to complete the fortifications and set up their artillery. On March 17, 11,000 British troops and some 1,000 Royalists departed Boston by ship and sailed to the safety of Halifax, Nova Scotia.
The bloodless liberation of Boston by the Patriots brought an end to a hated eight-year British occupation of the city, known for such infamous events as the "Boston Massacre." For the victory, General Washington, commander of the Continental Army, was presented with the first medal ever awarded by the Continental Congress.