Between November 1775 and February 1776, Colonel Henry Knox and a team of engineers used sledges to retrieve 60 tons of heavy artillery that had been captured at Fort Ticonderoga, bringing them across the frozen Hudson and Connecticut rivers in a difficult, complex operation. They arrived back at Cambridge on January 24, 1776. Some of the Ticonderoga cannons were of a size and range not previously available to the Americans. They were placed in fortifications around the city, and the Americans began to bombard the city on the night of March 2, 1776, to which the British responded with cannonades of their own. The American guns under the direction of Colonel Knox continued to exchange fire with the British until March 4.

On March 10, 1776, General Howe issued a proclamation ordering the inhabitants of Boston to give up all linen and woolen goods that could be used by the colonists to continue the war. Loyalist Crean Brush was authorized to receive these goods, in return for which he gave certificates that were effectively worthless.^[25] Over the next week, the British fleet sat in Boston harbor waiting for favorable winds, while Loyalists and British soldiers were loaded onto the ships. During this time, American naval vessels outside the harbor successfully captured several British supply ships.^[26]

On March 15, the wind became favorable for the British, but it turned against them before they could leave. On March 17, the wind once again turned favorable. The troops were authorized to burn the town if there were any disturbances while they were marching to their ships;^[25] they began to move out at 4:00 a.m. By 9:00 a.m., all ships were underway.^[27] The fleet departing from Boston included 120 ships, with more than 11,000 people on board. Of those, 9,906 were British troops, 667 were women, and 553 were children.^[28]