Answer:
The answer to this question is the alliance with France.
Explanation:
During the American Revolution, the war had been in Britain's favor until the Battle of Saratoga. This battle proved to be a successful American victory which convinced France to ally with Americans. The French had provided supplies, arms, ammunitions, and military support to the American army. This alliance was a main political factor had helped turn the war in favor of America, leading to the eventual independence from Britain.