Since the Battle of Bunker Hill, there had been no major clash between the armies facing each other at Boston. General Washington devoted himself to the daunting problems of feeding, arming, and reinforcing his army. General Gage was quiescent. The British high command was coming to the recognition that the occupation of Boston was a strategic cul-de-sac. Any advance from the city would mean more assaults on fortified hills, and jaunts through a distinctly unfriendly countryside. Operations elsewhere, especially in New York, seemed to offer more promising military possibilities. When news of Bunker Hill reached London, the ministry lost what little confidence in Gage that it had left and recalled the General for consultations, a face-saving way of shelving him. General Howe replaced Gage in October. In the short run, the change in command made little difference. Howe had no more stomach for adventures in Massachusetts than his predecessor. He settled down for the winter.

Over the winter of 1775–76, Washington's worries about the survival of his force were abated slightly by the enlistment of a portion of his command in the Continental army for a twelve-month term of service. Washington wanted to strike the British, but his lack of artillery was crippling. The only source of artillery was Ticonderoga, 300 miles away.

Washington sent his artillery commander, Henry Knox, to fetch the army some cannons. Knox was a young man who had been a bookseller before the war. All he knew of the military life came from books. Despite this, he was already proving to be an able military engineer and gunner. Knox traveled to Ticonderoga and had fifty-nine cannon and mortars loaded on sledges. They were then dragged overland through the winter snow, up and down hills, and through roadless wilderness to Washington's camp. Knox's feat made possible a decisive blow against the British. On the night of March 4–5, 2,000 American troops occupied and fortified Dorchester Heights. With Knox's guns emplaced there, the position of the British army and fleet was untenable.

Howe believed that honor demanded an assault on Dorchester Heights. He was ready to attack March 5, but a downpour of rain that lasted two days spared both sides a bloodbath. Howe decided to evacuate on March 7. This was what he and his army had long wanted anyway.

Washington was content to let him go peacefully. Howe set sail for Halifax on March 17, taking along with his army more than 1,000 loyalists who were unwilling to stay behind.