For 11 months, colonial militia trapped the most powerful army in the world inside a single city — then forced them to leave without firing a shot.
The day after Lexington and Concord, thousands of New England militiamen surrounded Boston, trapping 10,000 British troops inside the city. What began as a spontaneous uprising quickly became an organized siege under General George Washington.
The standoff stretched 11 months, with neither side able to deliver a decisive blow. The British held the city; the Americans held the roads. Disease, hunger, and boredom plagued both sides.
The turning point came from an unlikely direction: a 25-year-old bookseller named Henry Knox. Washington sent Knox to retrieve cannons from Fort Ticonderoga, 300 miles away in upstate New York. Knox dragged 60 tons of artillery through the winter wilderness on sleds.
On the night of March 4-5, 1776, American troops secretly hauled Knox's cannons to the top of Dorchester Heights — a commanding hill overlooking the harbor — and built fortifications overnight. British General Howe woke to find his entire fleet in the crosshairs.
Howe recognized immediately that his position was untenable. He had two choices: launch a costly uphill assault or leave. He chose to leave. On March 17, 1776, 120 ships carrying 11,000 soldiers and Loyalist civilians sailed for Halifax, Nova Scotia.
Boston's liberation was America's first major military victory of the Revolution, achieved without a single battle after the fortification of Dorchester Heights. It proved that Washington's army, though untested, could force the British to yield strategic ground.