American Revolution/Evacuation of Boston

Fortification of Dorchester Heights
On July 3, George Washington arrived to take charge of the new Continental Army. Forces and supplies came in from as far away as Maryland. Trenches were built at the Dorchester Neck, and they were extended toward Boston. Washington reoccupied Bunker Hill and Breeds Hill without opposition. However, these activities had little effect on the British occupation. Subsequently, in the winter of 1775–76, Henry Knox and his engineers used sledges to retrieve 60 tons of heavy artillery that had been captured at Fort Ticonderoga. Bringing them across the frozen Connecticut River, they arrived back at Cambridge on January 24, 1776. Weeks later, in an amazing feat of deception and mobility, Washington moved artillery and several thousand men overnight to occupy Dorchester Heights, overlooking Boston.

Since it was the middle of winter and the continental army was unable to dig into the frozen ground on Dorchester Heights, rather than entrenching themselves, Washington's men used logs, branches and anything else available to fortify the position overnight. General Gage observed that it would have taken his army weeks to build Washington's earth fort. The British fleet ceased to be an asset, because it was anchored in a shallow harbor with limited maneuverability, and the American guns on Dorchester Heights were aimed at the fleet.

Washington had hoped General William Howe and his troops would either flee or try to take the hill. At early morning on March 5, Washington rallied the troops by reminding them that it was the sixth anniversary of the Boston Massacre. Initially, Howe ordered an attack on the hill that would have probably been reminiscent of Bunker Hill. However, a snow storm quickly rolled in and halted any chance of a battle. By the time the storm had subsided, Howe's aides had convinced him of the folly of an outright attack.

He sent word to the colonists that the city would not be burned to the ground if they were allowed to leave unmolested. Finally, on March 17, the British forces departed Boston and headed to Halifax, Nova Scotia, taking many loyalists with them.