the task of directing the unit's transport, complicated by the requirement to move at night with equipment and personnel to be drawn by horse and mule. After Saint-Mihiel, the unit was moved to Verdun where hundreds of thousands of French and Germans had become casualties earlier in the war. This would become the last major engagement of the First World War for Middleton, who was promoted to lieutenant colonel on 17 September, shortly before the commencement of the operation, called the Meuse-Argonne Offensive. Meuse-Argonne Offensive The 4th Division, on its own for the first time in the war, was assigned a front that was one to two miles wide, sandwiched between two seasoned French divisions, about eight miles from Verdun. Lieutenant Colonel Middleton's battalion led the attack for the Americans on 26 September 1918. That day, they covered five miles, breaking through German defenses, after which it was up to the entire 47th Infantry Regiment to hold onto the gains. Middleton then put his second-in-command in charge of the battalion when he was assigned as the executive officer of the regiment. He was in this staff position for two weeks when, on 11 October, he was given command of the 39th Infantry Regiment after commander James K. Parsons and most of his regimental staff became casualties following a gas attack. At about one o'clock in the morning, Middleton had to find his way to the 39th headquarters and prepare for battle at daybreak. Shortly before 7:30 a.m., Middleton led his new regiment into enemy-held territory using a tactic called "marching fire," where all of the troops constantly fired their weapons while moving a mile through heavy woods. This compelled most of the dug-in and concealed Germans to surrender, and allowed the 4th Division to move to the edge of the Meuse River. Three days after taking command of the 39th, and two days after his twenty-ninth birthday, Middleton was promoted to colonel, becoming the youngest officer in the American Expeditionary Forces (AEF) to attain that rank. He also received the Army Distinguished Service Medal for his exceptional battlefield performance. The citation for the medal reads: On 19 October, the 4th Division was withdrawn from the battle line after 24 days of continuous contact with the enemy, the longest unbroken period of combat for any American division during the war. Middleton was now given command of his former regiment, the 47th.