In the summer of 1777, a second British army, led by General John Burgoyne, advanced south from Canada hoping to link up with Howe and isolate New England. But in July, Howe instead moved his forces from New York City to attack Philadelphia. In September, the Continental Congress fled to Lancaster, in central Pennsylvania, and Howe occupied the City of Brotherly Love. Not having been informed of Burgoyne’s plans, Howe had unintentionally abandoned him. American forces blocked Burgoyne’s way, surrounded his army, and on October 17, 1777, forced him to surrender at Saratoga. The victory provided a significant boost to American morale.
During the winter of 1777-1778, the British army, now commanded by Sir Henry Clinton, was quartered in Philadelphia. (In the Revolution, as in most eighteenth-century wars, fighting came to a halt during the winter.) British officers took part in an elegant social life complete with balls and parties. Most notable was the great Meschianza, an extravaganza that included a regatta, a procession of medieval knights, and a jousting tournament. Meanwhile, Washington’s army remained encamped at Valley Forge, where they suffered terribly from the frigid weather.
But Saratoga helped to persuade the French that American victory was possible. In 1778, American diplomats led by Benjamin Franklin concluded a Treaty of Amity and Commerce in which France recognized the United States and agreed to supply military assistance. Still smarting from their defeat in the Seven Years’ War, the French hoped to weaken Britain, their main European rival, and perhaps regain some of their lost influence and territory in the Western Hemisphere. Soon afterward, Spain also joined the war on the American side. French assistance would play a decisive part in the war’s end. At the outset, however, the French fleet showed more interest in attacking British outposts in the West Indies than directly aiding the Americans. And the Spanish confined themselves to regaining control of Florida, which they had lost to the British in the Seven Years’ War. Nonetheless, French and Spanish entry transformed the War of Independence into a global conflict. By putting the British on the defensive in places ranging from Gibraltar to the West Indies, it greatly complicated their military prospects.