Black Bear and his northern band suffered the brunt of a campaign of three columns sent into the Powder River country of northern Wyoming and southern Montana against the allied northern tribes in August 1865, by General Patrick E. Connor.
Although the 3,000 troops managed to engage the Sioux and Cheyennes in minor, inconclusive skirmishes, generally to their own disadvantage, they attacked and routed Black Bear’s people, killing many men, women, and children; they then proceeded to burn their tepees and possessions.
The invading army was repelled from the Powder River country in September by hit-and-run Indian raids plus stormy weather.
Yet the abortive campaign had a long-lasting effect: It further sealed the military alliance of the Northern Arapahos with the Sioux and Cheyennes.
The massacre of Cheyenne innocents at Sand Creek one year earlier, in September 1864, witnessed by a number of Arapahos, had done the same for the southern group.
At the end of the wars the Southern Arapahos were placed on a reservation with the Southern Cheyennes in the Indian Territory; the Northern Arapahos, however, ended up on the Wind River reservation in Wyoming with the Northern Shoshoni, once their enemies.