Final answer:
Joseph Brant, or Thayendanegea, was a Mohawk leader who acted as a translator and played a significant role in aligning some Iroquois nations with the British during the American Revolutionary War. Post-war, he aimed to protect Native lands by forming the Western Confederacy.
Step-by-step explanation:
During the American Revolutionary War, Mohawk leader Joseph Brant, also known as Thayendanegea, did indeed work closely with the British forces. Brant was educated at a Christian Indian school and leveraged his multilingual abilities to serve as a translator for the British. He played a significant role in influencing the Iroquois Confederacy's decision-making regarding the war.
Joseph Brant was integral in aligning the Mohawk, Cayuga, Seneca, and Onondaga with the British, against the Americans. The Oneida and Tuscarora, however, sided with the American revolutionaries. After the war, Brant continued his efforts to protect Native interests, and in response to American expansion, he helped to form the Western Confederacy to resist American encroachment into their territories.