Sioux and Cheyenne warriors wipe out 81 U.S. Army soldiers near Fort Phil Kearny in Wyoming.

In present-day Powder River County, Wyoming, the strongly resisted U.S. Army incursion into Sioux and Cheyenne Territory had escalated into what later was called Red Cloud's War. Around the new Fort Phil Kearny, army wood cutting details were becoming routinely attacked.  Sent to the relief of such an attack, eighty-one men in a combined force of Second Cavalry troopers and Eighteenth Infantry, under the command of Captain William J. Fetterman, were decoyed into an ambush led by the Oglala Sioux war chief Crazy Horse. Every man in the detachment was killed giving the U.S. Army its heaviest defeat against Plains Indians up to that point. Native Americans called the victory the Battle of the Hundred Slain. (By John Osborne)