British Parliament enacted the Port Act in reprisal for the Boston Tea Party in March 1774. The first of the “Intolerable Acts,” the Port Act closed Boston harbor to all shipping until payment for the destroyed tea was made. In May, two additional “Intolerable Acts” forbade public meetings in Massachusetts unless sanctioned by the royal governor and transferred any trial of a British official accused of a capital offense to England or another colony.
In March of 1776, American forces captured Dorchester Heights, which overlooked Boston harbor. They proceeded to enhance their position with artillery captured from Fort Ticonderoga. Outflanked, the British were forced to evacuate Boston and set sail for Halifax, Nova Scotia.