In May 1857 preparation began for the expedition with the organizing of the 1st Cavalry under Colonel Edwin Vose Sumner at Fort Leavenworth. Sumner divided the regiment into two columns in order to circle the Cheyenne hunting grounds in central Kansas Territory. One column, under Major John Sedgwick, departed on 18 May with four companies, five Delaware scouts and forty wagons, heading west along the Arkansas River past Bent's Fort north up to the South Fork of the Platte River. There they were to meet Sumner's column, which had left Fort Leavenworth on 20 May, with four cavalry companies, 300 cattle and 51 wagons. Sumner's column went north and then west up to Fort Kearny, where three companies of the 6th Infantry Regiment and two companies of the 2nd Dragoons, five Pawnee scouts and ten more wagons were added. After considerable difficulty in crossing the South Platte River, Sumner's column and Sedgwick's columns met at the South Platte as planned on 4 July. The whole regiment then traveled east through central Kansas to their rendezvous with the Cheyenne on the Solomon river. The map in the inset shows the routes taken by both columns.