Two battles on July 26, 1865 near Platte Bridge Station near present-day Casper, Wyo., are best understood in the context of tribal response to the Sand Creek Massacre the previous November. Twenty-eight U.S. troops were killed that day including Lt. Caspar Collins, for whom Fort Caspar and the town of Casper were later named.
On Aug. 29, 1865, troops under Brig. Gen. Patrick E. Connor attacked an Arapaho village near present Ranchester, Wyo. Connor’s detachment was part of a large expedition ordered to subjugate the warring Cheyenne, Sioux and Arapaho in the Powder River Basin. Overall success was mixed. Connor was relieved of his command.