The document that declared the 13 American colonies free from British rule is the Declaration of Independence, adopted on July 4, 1776. Authored primarily by Thomas Jefferson, the Declaration articulated the colonies' grievances against King George III and asserted the natural rights of individuals, including life, liberty, and the pursuit of happiness. This revolutionary proclamation signified a bold assertion of self-governance and independence, fundamentally reorienting the relationship between the colonies and Britain, and inspiring future movements for independence and democratic governance around the world.