 After the Armistice was signed in November, Conner was assigned to the Army General Staff in Washington and was promoted to permanent colonel on August 22, 1919.In 1920, a subcommittee of the House of Representatives launched an investigation in the losses among United States Army personnel that had occurred in the hours between the time when the Armistice of 11 November 1918 had been signed and the time when it came into effect.During the hearings, Conner drew heavy criticism from Congressman Oscar E. Bland and was named by General John H. Sherburne of the Massachusetts National Guard as the individual most responsible for not stopping a scheduled attack by the 92nd Division of Robert Lee Bullard's Second Army.