The History of HArrison and Mercer Counties, Missouri, 1888, states "The Fifth Kansas Cavalry comprised two companies from Mercer County. Company B was organized near Ravanna, Mo., in July 1861, with John R. Clark as captain, Jacob Loutzenhizer, first lieutenant (succeeded before muster by A. J. McIntosh), J. J. Alley, second lieutenant, and E. J. Abrams, orderly sergeant. It was composed of men from several Home Guard companies, and was organized for the Eighteenth Missouri Infantry, but Col. Johnson, from Leavenworth, Kas., who was organizing a cavalry regiment, induced this company to enter his regiment.

Company C, of this regiment, was organized at Modena, in Madison Township, with Garrett Gibson as captain, James H. Summers, first lieutenant; C. G. Bridges, second lieutenant; and Wesley Beck, orderly sergeant. At the organization of the regiment, Summers became a major, and was succeeded by Bridges whose place was filled by O. H. P. Cox.

Captain John R. Clark was killed by gun-shot wound from the provost guard on May 21, 1862 at Springfield, Mo. when he and company bugler, A. J. Rice were intoxicated and insisted on a Mrs. Willis to get them a supper at her home. She refused which enraged Captain Clark, who was officer of the day, and he and Rice drew their pistols to force their way into her home. A guard stationed at the Willis home for protection, fired at Clark killing him instantly and Rice fired at the guard, missing him but killing the unfortunate Mrs. Willis. The guard fired again and shot Rice. The Burlington Weekly Hawkeye, June 7, 1862 reported "Capt Clark was a native of Sciota, Ohio, but moved to Grundy county in this state in 1836. He served in the Mexican war under Sterling Price, and was afterwards twice elected Sheriff of Grundy county." [St. Louis].