After Lexington and Concord, colonial militia units from Massachusetts followed British troops back to Boston. In the days that followed, militia from New Hampshire, Connecticut, and Rhode Island joined the Massachusetts militia to help confine British troops to the city. The siege lasted from April 19, 1775, until March 17, 1776. The siege was part of the Boston Campaign and included the Battle of Bunker Hill and the Fortification of Dorchester Heights. It resulted in the British evacuating Boston and Massachusetts.