American alliances after 1778

The capture of a British army at Saratoga encouraged the French to formally enter the war in support of Congress, as Benjamin Franklin negotiated a permanent military alliance in early 1778, significantly becoming the first country to officially recognize the Declaration of Independence. On February 6, 1778, a Treaty of Amityand Commerce and a Treaty of Alliance were signed between the United States and France.William Pitt spoke out in parliament urging Britain to make peace in America, and unite with America against France, while other British politicians who had previously sympathised with colonial grievances now turned against the American rebels for allying with British international rival and enemy.

Later Spain in 1779 and the Dutch 1780 became allies of the French, leaving the British Empire to fight a global war alone without major allies, and requiring it to slip through a combined blockade of the Atlantic. The American theater thus became only one front in Britain's war. The British were forced to withdraw troops from continental America to reinforce the valuable sugar-producing Caribbean colonies, which were considered more important.

Because of the alliance with France and the deteriorating military situation, Henry Clinton, the British commander, evacuated Philadelphia to reinforce New York City. General Washington attempted to intercept the retreating column, resulting in the Battle of Moundmouth , the last major battle fought in the north. After an inconclusive engagement, the British successfully retreated to New York City. The northern war subsequently became a stalemate, as the focus of attention shifted to the smaller southern theater.