The Franco-American War was a war fought almost entirely at sea between the United States and France. After the fall of the monarchy during the Revolution, the United States refused to pay their debts to the new republic on the grounds that it had been owned to the monarchy. France was outraged, and this lead to several attacks on American shipping, leading to strong retaliation.
The French had been a crucial ally of the United States ever since the Revolutionary War, starting in 1778 when they signed a treaty of alliance against the United Kingdom. However, in 1794, a revolution conquered the French monarchy, the American government signed a treaty with Britain that resolved several points of contention between the two ever since independence.