On March 4, 1776, troops from the Continental Army under George Washington's command occupied Dorchester Heights, a series of low hills with a commanding view of Boston and its harbor, and mounted powerful cannons there threatening the city and the Navy ships in the harbor. General William Howe, commander of the British forces occupying Boston, planned an attack to dislodge them. However, after a snowstorm prevented its execution, Howe withdrew instead. British forces, accompanied by Loyalists who had fled to the city during the siege, evacuated the city on March 17 and sailed to Halifax, Nova Scotia.