A hundred years ago today, the newly created First Army of the American Expeditionary Force went into battle for the first time, commanding its own sector in northeast France. The St Mihiel offensive, as it was known, was an operation to cut off the St Mihiel salient, a 200 square mile bulge of territory on the frontline which had been held by German forces since the opening weeks of the Great War in 1914. Patrick Gregory reports. 

Victorious US troops change a street sign in Vignuelles – the heart of the St Mihiel salient – from Hindenburg Strasse to Wilson U.S.A. (Photo: US National Archives & Records Administration – 55201512/Wikimedia Commons/public domain)

Posted on centenarynews.com 12 September 2018

It was a day long in the planning and imagination of General John Pershing: the moment his American Expeditionary Force could step out from underneath the shadow of its allies on the Western Front.

It was a full month since the American had reached agreement with Supreme Allied Commander Ferdinand Foch on the founding of the new First United States Army. But a lot had happened in those intervening weeks, including a number of tense encounters between the two men.

Pershing had already agreed the terms of his army’s first outing scheduled for early to mid-September: an assault on the St Mihiel salient in the Meuse département. Yet he had also now signed up for what would be a much larger endeavour in the Meuse-Argonne area only two weeks afterwards. That was 60 miles to the north-west: a huge undertaking, almost an overreach of his forces’ capabilities.

The task for planning these operations had fallen to the former operations officer of the 1st Division, George Marshall. Marshall, who in his later career would rise to the position of Army chief of staff directing strategy during WWII, had recently been co-opted onto Pershing’s staff to work under the general’s chief of operations Brigadier General Fox Conner.

Lt Col George C Marshall in France (National Archives/Wikimedia Commons)

The young lieutenant colonel was quickly having to adapt to the new, larger stage he was planning on: grappling with complex issues of services of supply and the maintenance of an army growing with every passing week. But now, more immediately, the task of co-ordinating two large, interconnecting operations in which the First Army was to make its debut.

The overall, joint plan would necessitate moving troops north-west towards the Meuse-Argonne even while the St Mihiel operation was still in play. But Conner, Marshall and colleagues still had to deliver on the latter. Preparations for St Mihiel were made for a three-way assault: from the south, from the west and on the tip of the salient itself; and it would involve a total of four corps. The main attack was to be led from the south by Joseph Dickman’s IV Corps, made up of the 1st, 42d and 89th divisions. They were slated to meet in the middle of the salient around the town of Vignuelles with troops of the 26th Division, part of the V Corps attacking from the west.

Also on the south side of the salient, and attacking from the right of Dickman’s divisions, Hunter Liggett’s I Corps was preparing to press home the advantage, securing lines behind and under these first thrusts. And finally, on the tip of the St Mihiel bulge, was to come the fourth thrust from French forces, the French Colonial II Corps moving in to take the town that bore the name of the salient, a town in German hands for four years.

Battle of St Mihiel Map (Image: Via Wikimedia Commons, by ṜέđṃάяķvίʘĨїήīṣŢ CC BY-SA 3.00)

Added to the mix of ground forces, the commander of the US Air Service in the Zone of Advance Colonel Billy Mitchell, had drawn together the largest concentration of Allied air assets assembled in the course of the war: 1,481 planes and 21 balloon squadrons drawn from the US, France, Britain and Italy.

However, unbeknownst to the attackers, and just as the Americans were finalising their plans, Ludendorff had made plans of his own to evacuate German forces from the territory. Of the two lines within the salient – the forward Wilhelm Line and more heavily fortified rearward Michel Line – Ludendorff had concluded that the time was right to withdraw from the former to flatten out the front and conserve his forces’ strength. The withdrawal began on 11 September with some heavy artillery being moved just as American troops ringing the area were taking up their final positions to move in.

The moment of the attack had arrived. A battle order set days earlier, Field Order Number 9, stated simply: ‘The First Army will attack at H hour on D day with the object of forcing the evacuation of the St Mihiel Salient’; the first known use of the term by the US military.


An hour into 12 September the artillery barrage began, the fire directed onto German lines by the 2,900 Allied artillery pieces assembled; and four hours later the troops began their assault, advancing behind what had by now settled into a rolling barrage.

So what of the assault? Was it a foregone conclusion? A sledgehammer to crack a nut? Certainly a fearsome array of firepower had been assembled against an area the Germans were already minded to abandon. The troop levels – over half a million AEF and more than 100,000 French soldiers – were arguably always going to be greater than strictly necessary; especially in the context of the looming Meuse-Argonne campaign.

But Pershing did not regard this first outing of the First Army as a mere dress rehearsal or a trial run; and he was unaware of Ludendorff’s intentions. This for him was the real thing. It was necessary to deal with this salient, small as it was, in a quick and decisive manner. He felt the eyes of Allied commanders as well as the American administration and public on him and he wanted the job done properly.


In the face of the ongoing attack, the German High Command ordered front lines to be held while an orderly evacuation continued; but their forces were quickly overrun. The US 1st Division had achieved its first day objectives of Nonsard and Lamarche by 1200 noon and were ordered to press on to Vignuelles. The 26th Division was making similarly rapid progress from the west and reached Vignuelles by the early hours of 13 September. By dawn its troops had met up with the French 39th Division just south of them and later in the morning with the 1st Division.

Other territory and villages to the east were being taken by the 42d ‘Rainbow’ Division, crossing the river of Rupt de Mad along with the 89th Division, the latter capturing the town of Thiaucourt with the 2d Division. Mopping up operations continued into 15 and 16 September, but to all intents and purposes the salient was closed in these first two days. In total, some 7,000 AEF troops were killed or wounded during the operation but the retreating German forces had left behind 450 artillery pieces in their retreat, losing 15,000 of its own soldiers as prisoners in the process.

A relieved Pershing hailed the “willpower and strength” of his troops; and from Washington Wilson telegrammed his thanks on the “brilliant achievements” of his Army.

It had been a good first outing, but Pershing knew sterner tests lay in the weeks ahead.

Patrick Gregory is co-author with Elizabeth Nurser of An American on the Western Front: The First World War Letters of Arthur Clifford Kimber 1917-18 (The History Press 2016) American on the Western Front & @AmericanOnTheWF

Images:  Change of street sign – US National Archives & Records Administration – 55201512/Wikimedia Commons/public domain 

Lt Col George Marshall – National Archives/Wikimedia Commons/US Army photographer/public domain

Battle of St Mihiel Map – By ṜέđṃάяķvίʘĨїήīṣŢ CC BY-SA 3.00, Creative Commons – Attribution ShareAlike, via Wikimedia Commons