Each year on March 17, Boston marks Evacuation Day, commemorating the day British forces withdrew from the city in 1776, ending the Siege of Boston and delivering one of the first major strategic wins for the Patriot cause.
After the first fighting of the Revolution in 1775, British troops held Boston while American forces surrounded the city for months. The standoff dragged on until early March 1776, when George Washington’s army fortified Dorchester Heights, the high ground overlooking Boston Harbor. With cannon positioned there, the Americans could threaten British defenses and ships in the harbor—suddenly making Boston far harder for the British to hold.
On March 17, 1776, the British evacuated Boston by sea, departing for Nova Scotia. The outcome was a major morale boost and helped establish Washington’s leadership early in the war.
Today, Evacuation Day is still observed in Greater Boston and is a civic holiday in Suffolk County, Massachusetts (and observed by some local schools and offices).