He entered the army, and in 1916 he was commissioned as a
second lieutenant with the
16th Cavalry Regiment on 29 November 1916, and subsequently promoted to
first lieutenant. He was stationed at
Mercedes, Texas, on the Mexican border. He was transferred to the Third Cavalry in June 1917, was promoted to
captain on 17 October 1917.
World War I Allen was sent to France with the
3rd Cavalry Regiment with the
American Expeditionary Force under command of General
John J. Pershing. From November 1917 to January 1918, Allen was an aerial observer with the First Observation Squadron, Aviation Section,
Signal Corps. In January 1945, the 12th AD engaged in pitched battle seeking to regain ground along the southern Rhine lost during Germany's
Operation Nordwind, which was an attempt by German forces to recapture
Strasbourg. On 5 January 1945, the German
XIV Corps under General Otto von dem Bach established a bridgehead across the Rhine at Gambsheim with the
553rd Volksgrenadier Division and German
405th Infantry Division, along the southern flank of the Allied
VI Corps, while the
U.S. 79th Infantry Division attempted unsuccessfully to contain the bridgehead. The Germans sent the
Eighth Mountain Division across the Rhine further north on the following day, attempting to split the American defenses of the
XV Corps and
VI Corps, now fighting both to its northern and southern flanks. In response, the Seventh Army's Gen. Patch released the 12th Armored Division Company Command B (CCB), commanded by Col. Charles B. Bromley, to VI Corp to join the 79th ID. Unable to advance through
Herrlisheim, CCB withdrew to a complex known as la Breymuehl, (Fr: "the Waterworks"), at the intersection of an intact bridge over the
Zorn River. Company B suffered a 50% casualty rate. The 714th Tank Battalion reached the Zorn and attempted to provide cover, but well-directed anti-tank artillery decimated the Medium
Sherman M4A3 tanks, which withdrew from Herrlisheim after taking heavy losses. was down to a strength of only 150 men. Late in the afternoon of 10 January, Gen. Allen ordered CCB to renew its attack to reduce the bridgehead, but Col. Bromley recommended attempting to contain the bridgehead and let the Germans wear themselves out trying to sustain it. Gen. Allen then relieved Col. Bromley of command, but later restored him to his position and ordered the evacuation of Herrlisheim. The next day as 10th SS Panzer Division attempted to exploit its victory to the west of the town, however they sustained heavy losses as the US forces slowly withdrew and was replaced by the
36th Infantry Division. The town of Herrlisheim was finally liberated on January 31 as the Germans retired after the overall failure of their offensive. Under Gen. Allen's command, the 12th AD accompanied the
XXI Corps into Austria, capturing
Nuremberg and then
Munich, ending the war around the area of
Ulm. ==Personal life==