the native officer shown several times in the movie lincoln was ely parker. a full blood iroquois from the seneca nation. parker was aide de camp to grant. grant had to personnaly intercede to let him join the army as natives were barred from american military service at the time. parker was most well know for his stoic demeanor under fire and in the worst deisaters, and was a help to grant at these times when grant would often retreat into the bottle. parker is most famous for writting the draft terms of surrender of the confederacy at appamattox.parker mustered out as a full colonel if i remember correctly and was one of the finest union officers. ir was even said thst there were a few occasiona when grant was too deep in drink, parker would direct the war effort personally.

parkers presence at appomatox was a grievous insult to the confederaste officers who were avowed and open white supremists, but grant insisted he he there as he wrote the terms of surrender and was the chief aide de camp. lee did not object when they got to the famous court house, but then he was defeated.

of course nothing in american history is an aid or liberating to natives. the american and canadian nations are based on an unrequited and unacknowledged genocide. lincoln was a man of his time. you could not give legal rights to natives and build the america they lived in. at least lincoln started the liberation of the african slaves. unfortunately it took untill lyndon johnson to finish it with the civil rights act.