France became the first foreign ally of the United States during the Revolutionary War.
The Franco-American Alliance was signed on February 6, 1778, after the American victory at Saratoga convinced France that the rebellion had a serious chance of success. The agreements included a treaty of amity and commerce and a treaty of alliance against Great Britain.
French assistance was military, financial, and naval. France supplied weapons, money, troops, and ships, while French forces later fought alongside American troops in the Yorktown campaign. The French fleet's role in controlling Chesapeake Bay helped prevent British forces from relieving Cornwallis.
The alliance had a complicated political background. France wanted to weaken Britain after losing the Seven Years' War, while American leaders sought international support for independence. The alliance also helped internationalize the conflict, drawing Spain and the Dutch Republic into the wider war, although France was the first to form a formal alliance with the United States.