What is the relationship between Charles and Senator Dawes?

Charles was Senator Dawes' poster child for assimilation.... a Native American who'd graduated from medical school. Over time, however, the two became opponents, as Charles stood against forcing his people to adapt.... to own land that they believed belonged to no one. Charles believed and professed that if Dawes was willing to take each individual under his care, he might achieve his end, but that giving out parcels of land was not going to educate or change the lives of anyone.

“Must they adapt, sir, to the point of their own extermination?”