Actions have consequences, and representatives of nations and states have long memories. The British expelled France from the New World in 1763. Fifteen years later, France was more than ready to do what it could to even the score. Adhering to the usual code of ethics among states, it did so surreptitiously and more-or-less deniably, until Saratoga. Then the French court decided to roll the dice.
Among the consequences of that throw for the French were brief, sweet revenge; bankruptcy; the need to call the Estates General if the state were to levy any new taxes; the French Revolution; the Reign of Terror, Napoleon. In short, 20 years of exsanguination leading to defeat far more complete and irredeemable than it had inflicted on the British in 1783.
It worked out better for the Americans.
(It even worked out better for the British, in a backward sort of way. The defeat, including even temporary loss of command of the sea, was so shocking, and exposed deficiencies in so many aspects of military, naval, financial and general administrative procedures that, for once, sweeping reforms followed. It is argued by historians that without those reforms, England would likely have lost to France in the revolutionary and Napoleonic Wars that were soon to follow. Thus, the defeat in North America was a blessing in disguise. However, it is unlikely that in 1783 many Englishmen could see the blessing for the disguise.)
People often speak foolishly of friendship among nations. There is no such thing, and cannot be any such thing. Nations do not have friends; they have interests. Nations may have interests that run parallel for dozens, even occasionally for hundreds, of years, but when their interests change, their “traditional historic friendships” will change as well. And It’s worth remembering, in looking at the history of alliances and changes of alliances and accusations of betrayal.
It was in France’s interest to weaken England. Detaching a part of the British empire and helping it to become a powerful seafaring rival (even if it also spoke English and shared long political and cultural traditions) would serve that goal. The only question was, was it feasible? America sent lovable, plausible Ben Franklin to Paris to plead its case. The French adored Franklin. In modern parlance, they “got his act.” But no number of Ben Franklins – even if there had been more than one – would amount to a hill of beans without some evidence that the colonials could stand up to the English on the field of battle. Sniping at them from behind trees and rock walls was well and good, but for the French court to place its bet, it required stronger evidence of valor than Lexington or Concord, more persuasive evidence of America’s staying power than Washington’s ability to keep his army in the field.
Then came Saratoga. An entire British army outfought, surrounded, and captured. Could there be more convincing evidence that the Americans had a chance?
The French court had already been providing arms and ammunition. (For example, a French private citizen acting at the request of King Louis XVI and his foreign minister set himself up as a Portuguese company, sent gunpowder and ammunition to the neutral Dutch port of Saint Eustatius in the West Indies, and somehow this material wound up being used by the American army. It is easy to imagine the protestations: “But how could that have happened? How regrettable, monsieur. I assure you, the government had no knowledge of any such transaction.” But it was that powder and shot that helped defeat Burgoyne.)
In any case, in the aftermath of Saratoga, the French conferred recognition (on February 6, 1778), signed a military alliance, declared war on Britain (and roped in Spain and the Netherlands as allies) and came across with money, arms and soldiers. They also sent their navy, which after a couple of years managed to be in the right place at the right time (September 5, 1781) to bring about Yorktown (October 19), and the consequent fall of the British Tories and the rise of the Whigs, who were anxious to make a generous peace with the former colonies.
Oh, and about friendship among nations? America and France, in making their alliance, mutually pledged to make no separate peace. Naturally, each side immediately began worrying that the other side would do just that. The Americans, none of whom had fallen off the turnip truck, were well aware that they were in danger of being hung out to dry by a French court pursuing its own interests. Dr. Franklin and company stole a march on them and came to agreement with the English on their own.
Nations don’t have friends, they have interests.