King George III began tightening control over the colonies after the costly French and Indian War, leading to new taxes like the Stamp Act that upset colonists. In response to the Boston Tea Party, the Intolerable Acts closed Boston harbor until taxes were paid. On April 19, 1775, the American Revolution began with shots fired at Lexington and Concord leading to the siege of Boston. In July 1776, after Common Sense made the case for independence, the Declaration of Independence was signed in Philadelphia, declaring America independent from Britain.