For years after the battle, Indian survivors told how bravely the troopers fought. They did this because for a long time they believed they would be hanged if they said anything unflattering about the wasichus. Some troopers did fight bravely; others, probably a considerable number, panicked. Some simply lay down and waited to be killed. Some were killed running. Some shot themselves, or each other. It's possible, but not provable, that Captain Tom Custer shot his brother in the head.
"Save the last bullet for yourself," was their motto.