In early March 1776, Colonel Henry Knox arrived with heavy artillery captured from a raid on Fort Ticonderoga. Under the cover of darkness Washington placed his artillery atop Dorchester Heights March 5, threatening Boston and the British ships in the harbor. Howe feared another battle like Bunker Hill, so he evacuated Boston. The British were permitted to withdraw without further casualties on March 17 (known as Evacuation Day), and they sailed to Halifax, Nova Scotia. Washington then moved his army south to New York.