The event that altered the course of American history on July 4, 1776, was the adoption of the Declaration of Independence. Drafted primarily by Thomas Jefferson, the Declaration articulated the colonies' grievances against British rule and asserted their right to self-governance. By declaring independence, the thirteen American colonies aimed not only to liberate themselves from British control but also to articulate the principles of life, liberty, and the pursuit of happiness. This seminal document marked the beginning of the United States as a sovereign nation, setting the stage for the Revolutionary War and the eventual establishment of democracy.