The royal government of the Province of Massachusetts Bay existed until early October 1774, when members of the General Court met in contravention of the Massachusetts Government Act and established the Massachusetts Provincial Congress which became the "de facto" government. Governor Gage continued an essentially military authority in Boston, but the provincial congress governed the rest of Massachusetts. War finally erupted in April 1775 at Lexington and Concord, which started the American Revolutionary War and the Siege of Boston. The British evacuated Boston on March 17, 1776, ending the siege and bringing the city under Patriot control.