To be precise, it was the 2nd Colorado Infantry that was in Indian Territory in the summer of 1863. The 2nd and 3rd CO Inf were then combined to form the 2nd CO Cav in late 1863.... as I understand it. In Price's Missouri Expedition, the 2nd Colorado Cavalry followed Price to the Arkansas River in the Cherokee Nation. They then returned to Kansas via Ft Gibson and the Ft Gibson - Fort Scott Military Road.