The Constraints and Challenges of the St. Mihiel Offensive

1st Division Troops Prior to Launching the Offense

By Major Joshua M. Betty, U.S. Army

[Around the end of July 1918] he designated officers of the American First Army staff began moving into their new headquarters (GHQ) at the same time the commanders of the Allied armies met to discuss the upcoming offensives. Marshal Foch, recorded in notes by the GHQ, AEF staff, made a point of discussing a number of different future operations, including the clearing of German forces around the Paris-Avricourt railroad in the area of the St. Mihiel salient. The reduction of the St. Mihiel salient would fall to the newly formed American First Army. The reduction of the salient and the operations in the surround area would be the first by the American First Army as a distinct and unique force. The operation would combine divisions and corps with experience on the Western Front and those newly arrived in France. Even though the salient had stood in German hands since 1914, it would be a resounding American success. The next tasks for the GHQ, AEF and the American First Army were to develop a plan for the St. Mihiel operation.   

The planning for the reduction of the St. Mihiel salient began after the conference of the commanders-in chief at the end of July, but as is often the case in war,  the situation on the front changed. Marshal Foch determined an operation in the area between the Marne and the Meuse was now of the utmost importance and should take precedence over any operation in the St. Mihiel area. On 30 August 1918, he visited the headquarters of General Pershing and informed him the operation the nascent American First Army had been planning near St. Mihiel was no longer a priority. He stated the American forces would be needed further north to support French operations in September. General Pershing was determined to maintain the American First Army as a separate entity and to conduct the operation at St. Mihiel. 

French Trenches on the Meuse Heights Where  the
26th "Yankee" Division Launched Their Opening Attack

He was given a day to think over the discussion with Marshal Foch. He responded with a plan that would enable the operations at St. Mihiel and support the French plan in the Meuse area during September. The changes General Pershing purposed would have far-reaching consequences for his own force and would set in motion the largest logistical movement of troops in the American Army’s history. 

General Pershing’s response to Marshal Foch’s 30 August 1918, memorandum about the dispersal of American divisions and the cancelling of the St. Mihiel offensive was for the American Army to assume more of a role in the current fight. He insisted the St. Mihiel operations should continue and presented a plan that would include the involvement of the American First Army to support the operation in the Meuse-Argonne sector. General Pershing argued against Marshal Foch’s proposal of moving the St. Mihiel division north because it could not be accomplished by mid-September. He stated instead the St. Mihiel operations should continue, and the American Army could then shift its additional divisions, not involved in St. Mihiel, to the area north of Verdun and support the offensive with the required force between 20 and 25 September 1918. This plan would involve the American Army in two large offensives in a very short amount of time. 

 

After two days of deliberation, Marshal Foch responded to General Pershing’s plan and approved of the American offensives in both the St. Mihiel region and the Meuse-Argonne sector. The initial planned dates of attacks were 10 September and between 20 and 25 September, respectively. With the plan for the St. Mihiel operation confirmed the staffs of the GHQ, AEF and the American First Army finalized the details of the attack. The staffs had planned for nearly a month for the reduction of the salient; however, the addition of the offensive following in quick succession to the St. Mihiel operation added a new dimension to the attack all together. 

The movement from St. Mihiel to the Meuse-Argonne posed a major problem that needed special attention above planning for the rest of the operation. The task fell to Colonel George Marshall, attached to the Operations Section of the American First Army from the AEF, GHQ. 

About ten minutes’ consideration made it apparent that to reach the new front in time to deploy for a battle on September 25th, would require many of these troops to get under way on the evening of the first day of the St. Mihiel battle, notwithstanding the fact that the advance in that fight was expected to continue for at least two days. This appalling proposition rather disturbed my equilibrium and I went out on the canal to have a walk while thinking it over. 

 George C. Marshall, Memoirs of My Service in the World War: 1917-1918

In  the span of one evening, he developed a detailed plan of transferring the required troops and equipment from St. Mihiel to the staging points for the Meuse-Argonne offensive.  The massive logistical move of the large number of troops and equipment completed the orders for the reduction of the St. Mihiel salient. The plan of the American First Army called for three American and one French Corps to attack the St. Mihiel salient. Two of the American corps would attack from the south, one American corps would attack from the north, and one French division would attack east from the point of the salient in a large envelopment. The remaining divisions of the French Second Colonial Corps would hold the point of the salient. The great envelopment would involve twelve divisions in the line with an additional seven in reserve.  

American Troops Advancing on the Offensive's
Second Day

The next crucial step to the plan was the artillery barrage used to support the movement of the infantry. There was a large debate on how long the barrage should be and what was enough to maintain surprise and still be productive. As General Pershing remarked in his memoirs, after weighing the options he decided on a four-hour preparatory barrage. On 5 September 1918, Field Order No. 9 added the final touches to the combined arms efforts with the addition of both French and American tanks and the employment of Air Service Units to support the maneuver of the First Army. The American First Army published its orders and all the corps and divisions made the final preparations while they waited for the word to begin the initial operation of the American First Army.

At one o’clock in the morning four hours before the designated start time, the American First Army artillery barrage began pounding the German trenches and artillery positions. Then at five o’clock on 12 September 1918, the infantrymen of the American First Army began their assault behind a rolling artillery barrage. As the infantry reached the German wire positions, they used the cover of the rolling barrage to cut the wire and continue their attack, a tactic never before employed by the Allies.  The attack on the German positions in the St. Mihiel salient would continue throughout the day and into the next afternoon and prove extremely successful for the  American First Army and the AEF. By noon on 13 September, elements of the First American Army had closed the base of the salient and experienced only 5,000 casualties. At this time, the American Fist Army command asked Colonel George Marshall for his opinion on whether to continue the advance. He and Walter Grant, the Deputy Chief of Staff for the American First Army, made the following statement regarding further advancement, “Grant and I drew up a joint statement vigorously opposing any idea of such action." (emphasis added)  Marshall understood the situation of the American Army, as well as its other commitments for the Meuse-Argonne offensive was exceptional and his recommendation was no doubt one of the deciding factors for the remaining actions at St. Mihiel. 

Column of German Prisoners Captured on the First Day

 

Beginning on 13 September, the American First Army began firming up the line they had captured near Vigneulles on 12 September and over the next three days expanded their defensive positions further to the northeast. The American First Army took most of the large numbers of German prisoners, approximately 14,000, on the first day of the offensive. Gains by all divisions were much less in the successive days of the offensive leading up to 16 September. By the evening of 15 September, divisions were being withdrawn and sent north to participate in the coming Meuse-Argonne Offensive. The remaining troops established a defensive line from Haudiomont to Pont-à-Mousson. The establishment of the defensive line officially brought to a close the St. Mihiel offensive and the American First Army’s opening operation on the Western Front.  

The commanders and staffs of the American First Army turned their attention to the Verdun region after the second day of the St. Mihiel operation and prepared for the upcoming battle in the Meuse-Argonne.

Source:  The Operational Capability of the American Expeditionary Forces in the World War, Major Joshua M. Betty, US Army Command and General Staff College, 2014 

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