But the least plausible item in his catalog of gaudy deeds turns out to have been authentic : on today 's border between Wyoming and Nebraska in 1876 , within days of Custer 's last stand , Cody really did help lead cavalrymen within sight of a small band of Cheyenne warriors and then , while '' dressed in a stage costume of black velvet ... trimmed with silver buttons , '' managed to kill and scalp a subchief . ''