Other members of the peace commission were Lieutenant General William T. Sherman, commander of the Military Division of the Missouri; Major General William S. Harney (retired), who had taken part in earlier conflicts with the Cheyenne and Sioux along the Platte River; Brigadier General Alfred H. Terry, commander of the Military Department of Dakota; Senator John B. Henderson of Missouri, Chairman of the Senate Indian Appropriations Committee, who had introduced the bill that created the peace commission; Colonel Samuel F. Tappan, formerly of the First Colorado Volunteer Cavalry and a peace advocate who had led the U.S. Army's investigation of the Sand Creek massacre; Major General John B. Sanborn, formerly commander of the Upper Arkansas District, who had previously helped to negotiate the Little Arkansas Treaty of 1865. Sherman, having made public remarks indicating his disagreement with the peace policy, was called to Washington, D.C. and could not be present at the councils on the southern plains, including the council at Medicine Lodge Creek. Major General Christopher C. Augur, commander of the Military Department of the Platte, replaced him as a temporary appointment.