Evacuation Day in Boston marks the departure of the British on March 17, 1776, ending the 11-month “Siege of Boston.” This painting by Gilbert Stuart shows Washington at Dorchester Heights, where he surprised the British with new fortifications and cannons. The “Evacuation” took troops and Tory citizens to Halifax, NS. In Boston, Evacuation Day a local holiday, often combined with St. Patrick’s Day. Dorchester Heights is in South Boston.