The significant event that took place on July 4, 1776, was the adoption of the Declaration of Independence by the Continental Congress in Philadelphia. This document formally declared the thirteen American colonies free from British rule and articulated the colonies’ grievances against King George III. It marked a pivotal moment in the American Revolution, as it united the colonies in their quest for autonomy and self-governance. The Declaration, primarily authored by Thomas Jefferson, emphasized Enlightenment ideals of individual rights and government by consent of the governed, laying the groundwork for the democratic principles of the United States.