Final answer:
George Rogers Clark led men against the British and captured forts at Kaskaskia and Cahokia during the American Revolutionary War, altering the balance of power on the western frontier.
Step-by-step explanation:
The Man Who Captured Kaskaskia and Cahokia
The historic figure who led a group of men against the British into the west and captured forts at Kaskaskia and Cahokia was George Rogers Clark. Although the provided reference material does not specifically mention Clark, he is well-known in American history for his campaign in Illinois country during the Revolutionary War. Clark's small force of Virginia militia seized control of several British posts, which effectively weakened British influence in the region and bolstered the American frontier.
Clark's actions were significant as they not only gained territory for the burgeoning United States but also created a sense of disarray among the British and their native allies. This helped to shift the balance of power during a critical time in the American fight for independence. His campaign also demonstrated the strategic importance of the western frontier and its forts, such as Kaskaskia and Cahokia, in the broader context of the Revolutionary War.