Answer:
The Patriot militia leader that convinced many Native Americans to abandon their British allies, leading to the recovery of the fort at Vincennes, Indiana, was George Rogers Clark.
Step-by-step explanation:
George Rogers Clark was a Virginia soldier and was the highest-ranking US military officer on the northwest border during the American Revolutionary War. He is best known for his famous captures of Kaskaskia (1778) and Vincennes (1779), which significantly weakened British influence in the Northwest Territory. As the British ceded the entire Northwest Territory to the United States in 1783 through the Treaty of Paris, Clark is often referred to as the "Conqueror of the Northwest".