The United States came into existence as an independent nation in 1776 when the Declaration of Independence was adopted on July 4. This pivotal document, authored primarily by Thomas Jefferson, proclaimed the thirteen colonies' separation from British rule, striving for life, liberty, and the pursuit of happiness. The Declaration marked the birth of the United States and articulated the principles of governance based on the consent of the governed. The subsequent Revolutionary War, fought from 1775 to 1783, solidified this independence, establishing the U.S. as a sovereign entity and setting the stage for its future development as a nation.