In 1776, Thomas Paine wrote a pamphlet called "Common Sense". It argued that the colonies should be free of English rule. This was based on the English ideas of natural rights and social contract put forth by John Locke and others. On July 4, 1776, people from the 13 colonies agreed to the United States Declaration of Independence. This said that they were free and independent states, and were not part of England any more. The colonists were already fighting Britain in the Revolutionary War at this time. The Revolutionary War started in 1775 at Lexington and Concord. Though American soldiers under George Washington lost many battles to the British, they won a major victory at Saratoga in 1777. This led to France and Spain joining the war on the side of the Americans. In 1781, an American victory at Yorktown helped by the French led Britain to decide to stop fighting and give up the colonies. America had won the war and its independence.