The average American would probably be frustrated.
After this battle, every form of diplomatic activity with the Indians was over. The United States decided to "make a point" on the Native American question. This is because a significant massacre took place in which civilians were killed in addition to the soldiers. And if General Custer himself could probably have avoided the battle, people and I must have been frustrated by the massacre that happened to their citizens. Newspaper articles just reported in great detail about this event, which certainly caused anger at Americans, but certainly also made them sad about so many casualties.
you may have thought killing the Sioux in revenge was acceptable.
you may have believed that the Indian Wars were all the fault of the American Indians involved.
you may have been more likely to support the reservation system.
you might have been more willing to support the United States in the conflict.