On February 6, 1778, France and the fledgling United States of America signed the Treaty of Amity and Commerce and the Treaty of Alliance in Paris, France. The Treaty of Amity and Commerce recognized the United States as an independent nation and promoted trade between France and the United States. The Treaty of Alliance created a military alliance against Great Britain, stipulating American independence as a condition of peace. The treaty also required France and the U.S. to concur in any peace agreement.
Secretly aiding the American colonies since 1775, France's helpfulness was spurred by resentment over the loss of American territory to Britain in the French and Indian War. In 1776, the Continental Congress sent diplomats Benjamin Franklin, Silas Deane, and Arthur Lee to secure a formal alliance with France. American victory over the British in the Battle of Saratoga convinced the French that the Americans were committed to independence and worthy partners to a formal alliance. Over the course of the war, France contributed an estimated 12,000 soldiers and 32,000 sailors to the American war effort.
The Marquis de Lafayette, a French aristocrat, arrived in Philadelphia in July 1777 and offered his services to the Continental Army. Serving as a major general in the Continental forces, he quickly forged a life-long friendship with American commander in chief George Washington. After distinguishing himself on the battlefield, he returned to France early in 1779 and successfully urged the government to send a 6,000-man expeditionary army to the United States. Back in America by April 1780, Lafayette returned to the business of war, playing a key role in securing victory over British commander Lord Charles Cornwallis at Yorktown in late July.