The Connor Battlefield site is located in the small community of Ranchester. Originally an Indian campsite, its physical properties represent a well situated level and protected stretch of river bottom. Many large trees occupy the battle site with cottonwoods predominating. Three sides of the site are bordered by the Tongue River which flows in a meandering fashion along the west, north, and east sides of the campsite.

The Battle of the Tongue River, August 29th, 1865 (the site of which has now become known as the Connor Battlefield) represents the single most important engagement of the Powder River Indian Expedition of 1865. The Powder River Indian Expedition was a punitive military campaign conducted during that year to suppress the hostile Sioux, Cheyenne, and Arapahoe Indians committing depredations along the emigrant trails on the Northern Plains. Though the Tongue River Fight was a decisive victory for the military, the overall success of the Powder River Expedition was inconclusive. The direction of the general plan of the campaign was the responsibility of Major General Grenville M. Dodge, then in command of the Department of the Missouri. Brigadier General Patrick E. Connor was given command of the field operations.

Except for minor skirmishes with roving war parties Connor's forces made little contact with the hostiles until late August when a band of 500 Arapahoes under Chief Black Bear and old David was discovered on the Tongue River. At 7:30 on the morning of the 29th the attack began led by General Connor. Although the soldiers were outnumbered they managed to rout the Indians. The skirmishing lasted until after dark but Connor had destroyed the Arapahoes' capacity to wage war and had killed over sixty of their number including the son of Chief Black Bear. Seven women and eleven children captives were eventually released. This ended the Battle of Tongue River and for all practical purposes this also marked the end of the Powder River Indian Expedition. Today there are no physical remains of the battle in evidence.