The document that declared the colonists' independence from British rule was the Declaration of Independence, adopted on July 4, 1776. Drafted primarily by Thomas Jefferson, it articulated the colonies' grievances against King George III and asserted their right to self-governance. The Declaration established fundamental principles such as inalienable rights, including life, liberty, and the pursuit of happiness. By proclaiming their independence, the colonists sought to justify their break from British authority and inspire others toward liberty. The document became a cornerstone of American identity and a symbol of democratic ideals, influencing future movements for independence worldwide.