In 'Nations Collide,' Sitting Bull faces the challenge of uniting various Native American tribes to form an unprecedented resistance movement against the encroaching American settlers and U.S. Army, who are seizing native lands in the Great Plains after the Civil War. He must rally his people alongside warrior Crazy Horse to protect their land and way of life amid increasing tensions and conflict.

The episode portrays Sitting Bull and Crazy Horse as key leaders working closely together. Sitting Bull is shown as the Lakota leader stepping into a crucial role, while Crazy Horse is depicted as a fierce warrior. Together, they organize and lead the resistance movement against the U.S. Army's invasion of their lands.

American settlers and soldiers are depicted as invading the Great Plains, seizing Native American lands in the aftermath of the Civil War. Their arrival and land seizure are the primary catalysts for the conflict and resistance led by Sitting Bull and Crazy Horse.

Yes, the episode highlights the formation of a resistance movement that is unprecedented and inspiring, implying that Sitting Bull and Crazy Horse rally not only the Lakota but also other Native nations to unite in defense of their lands and culture against the U.S. Army.

While specific battle scenes are not detailed in the summaries, the episode centers on the mounting tensions and the organization of resistance by Sitting Bull and Crazy Horse in response to the settlers and soldiers invading and seizing native lands, setting the stage for confrontations between the Native resistance and the U.S. Army.