The French government regarded the American revolution as an opportunity to weaken the British empire. Since its defeat in the Seven Years' War, France had been rebuilding its military power and mending diplomatic fences. Humbling the arrogant British would be sweet revenge and would have the practical advantage of evening out the balance of power in Europe.

The French foreign minister, Charles Gravier, comte de Vergennes, saw the potential advantages of aiding the American rebels. A prudent statesman, he would not lightly risk the possibility of a disastrous war with Britain. Differences of opinion within the French government also inclined him to caution. King Louis XVI was dubious about helping enemies of a monarch with whom he was at peace. The Comptroller General of Finances, Baron Turgot, passionately declared that a war with Britain would push France into bankruptcy. Vergennes persuaded the King and his fellow ministers to agree to a policy that he considered both practical and safe, providing covert assistance to the Americans. A sum of 1 million livres was set aside for this purpose.

Vergennes approached his Spanish counterpart, the Marquis Grimaldi, about acting as a partner in the scheme. Spain had its own reasons for seeking vengeance against Britain. Grimaldi forwarded another million livres. As his agent in this covert operation, Vergennes chose Pierre-Augustin Caron de Beaumarchais, a man who excelled as an inventor, watchmaker, poet, playwright, man about town, and French spy. In the spring of 1776, Beaumarchais had set up a front called Roderigue Hortalez and Company to funnel munitions to the Americans. Beaumarchais proved brilliantly effective as an arms smuggler. Hortalez and Company supplied 80 percent of the powder used by the American army over the next two years.

Vergennes closely followed the course of the war in America. The prospects for French intervention rose or fell with American fortunes on the battlefield. Vergennes could only carry the King and his ministerial colleagues into war if it seemed certain that the United States would survive.

The Battle of Saratoga gave the French that assurance. The victory was greeted as joyfully in Paris as if it had been achieved by French arms. Beaumarchais was injured in a carriage accident as he excitedly rushed the news to the King.

In the wake of Saratoga, the British offered conciliatory terms to the Americans if they would resume their allegiance to the Crown. Franklin met with a British representative in Paris, and then shrewdly let the French know. Vergennes did not want to lose what seemed a golden opportunity to strike a heavy blow against Britain. He had come to believe that war was inevitable with France's ancient foe, and it was better to fight while the British army and navy were tied down in America. On December 17, Vergennes told the American commissioners that France would recognize the United States. His condition was that the United States would not make a separate peace.

Before Vergennes could formalize his promise, he had to consult with the Spanish. The new foreign minister, Count Floridablanca, was not as sanguine about the benefits of aiding the Americans as his predecessor. King Charles III and his ministers worried that a war in support of American revolutionaries would foment disturbances in Spanish colonies.

Unable to bring the Spanish with him, Vergennes moved alone. Turgot, the most formidable opponent of war, had been dismissed from office. Vergennes was able to secure the assent of Louis XVI and the rest of the ministry to an American alliance in January. On February 6, 1778, Vergennes, Franklin, Deane, and Lee signed two treaties. The first was a Treaty of Amity and Commerce that constituted formal French recognition of the United States and gave each country most favored nation status with the other. It was expected that this treaty would provoke a British declaration of war against France.

This would activate the second treaty, a Treaty of Alliance. According to its provisions, both nations would continue the war until the independence of the United States was “formally or tacitly assured.” Neither nation could make peace without the consent of the other. The United States was given a free hand to acquire Canada and Bermuda, while France could expand its possessions in the West Indies. Both nations guaranteed each other's territories in the western hemisphere.

The British reacted as expected, attacking French ships on June 16. Congress had rejected the British overtures for reconciliation as too little, too late. On May 4, it ratified the treaties with France. The French dispatched a minister to the United States, and Franklin became the first American minister to France. With the Franco-American treaties of 1778, the United States had won itself a recognized place in the informal concert of nations.