Yarmouth was the site of an active group of the Sons of Liberty during the American Revolution. The town's militia mustered to provide assistance to the minutemen at the Battles of Lexington and Concord, but the militia returned home upon news that the rebels had already triumphed on the field. In March 1776, Yarmouth troops served as part of George Washington's forces during the Fortification of Dorchester Heights. A meeting of Yarmouth citizens declared the town's independence from Great Britain on June 20, 1776. As a coastal community, Yarmouth was subject to blockade by the Royal Navy throughout the Revolutionary War.