Battle of Saint-Mihiel

The Battle of Saint-Mihiel was a World War I battle fought between September 12–15, 1918, involving the American Expeditionary Force and 48,000 French troops under the command of General John J. Pershing of the United States against German positions. The United States Army Air Service (which later became the United States Air Force) played a significant role in this action.

This battle marked the first use of the terms 'D-Day' and 'H-Hour' by the Americans.

The attack at the St. Mihiel Salient was part of a plan by Pershing in which he hoped that the United States would break through the German lines and capture the fortified city of Metz. It was one of the first U.S. solo offensives in World War I and the attack caught the Germans in the process of retreating. This meant that their artillery were out of place and the American attack proved more successful than expected. Their strong blow increased their stature in the eyes of the French and British forces, but again demonstrated the critical role of artillery during World War I and the difficulty of supplying the massive World War I armies while they were on the move. The U.S. attack faltered as artillery and food supplies were left behind on the muddy roads. The attack on Metz was not realized, as the Germans refortified their positions and the Americans then turned their efforts to the Meuse-Argonne offensive.

Background: Saint-Mihiel salient
Saint-Mihiel is a town in the Meuse department in north-eastern France. Since the end of the 1870 Franco-Prussian War the town was no longer considered important strategically and military installations were not developed. This changed early in World War I with the town inside the battlefront.

In 1914 the German command wished to take the Verdun fortifications which formed a strong point in the French lines. A first attempt, at Bois-le-Pretre (Priesterwald in German), failed despite violent fighting. During two more attempts (Battle of Flirey) German troops took Saint-Mihiel and the fort at Camp des Romains, but they were ultimately stopped at the Fort de Troyon to the south of Verdun.

During the course of the war the battlefront did not change much in this area. Saint-Mihiel formed a salient inside the French lines, blocking communications between Nancy and Verdun. The area near St. Mihiel would know much fighting: But despite French attacks the German forces were able to retain this strategic location until the last months of the war.
 * The Crête des Éparges (Les Éparges crest): February–April 1915.
 * The Bois d'Ailly (Ailly Wood) and the Tranchée de la Soif (Trench of Thirst): isolated behind German lines, Commander André's men fight three days without food or water before surrender in May 1915.
 * Bois Brûlé (The Burned Forest): many casualties when German conquer a redoubt on December 1914. It's here that the sub-officer Jacques Péricard pronounced the famous words: "Debout les morts!" (Dead men, arise!) on 8 April 1915.
 * The forêt d'Apremont (Apremont forest), the Tête à vache (Cow's head) trenches, Calonne trenches…

Prelude
General John Pershing thought that a successful Allied attack in the region of St. Mihiel, Metz, and Verdun would have a significant effect on the German army. General Pershing was also aware that the area's terrain setting first dictated that the restricted rail and road communications into Verdun (restrictions that had been imposed by the German attack during the Battle of Flirey) be cleared, and that a continuation of the attack to capture the German railroad center at Metz would be devastating to the Germans. After these goals were accomplished, the Americans could launch offensives into Germany proper.

Weather reports
The weather corps of Corps I Operation Order stated: "Visibility: Heavy driving wind and rain during parts of day and night. Roads: Very muddy." This would pose a challenge to the Americans when the order to advance was given. In some parts of the road, the men were almost knee-deep in mud and water. After five days of rain, the ground was nearly impassible to both the American tanks and infantry. Many of the tanks were wrecked with water leakage into the engine, while others would get stuck in mud flows. Some of the infantrymen developed early stages of trench foot, even before the trenches were dug.

German defensive positions
Prior to the American operation, the Germans installed many in-depth series of trenches, wire obstacles, and machine-gun nests. The battlefields' terrain included the nearby premises of three villages: Vigneulles, Thiaucourt, and Hannonville-sous-les-Cotes. Their capture would accelerate the envelopment of the German divisions near St. Mihiel. The American forces planned to breach the trenches and then advance along the enemy's logistical road network.

The Germans knew many details about the Allied offensive campaign coming against them. One Swiss newspaper had published the date, time, and duration of the preparatory barrage. However, the German Army stationed in the area of St. Mihiel lacked sufficient manpower, firepower and effective leadership to launch a counter-attack of its own against the Allies. Thus, the Germans decided to pull out of the St. Mihiel Salient and consolidate their forces near the Hindenburg Line. The Allied forces discovered the information on a written order to the German Group Armies von Gallwitz.

Allied tank support
Although the AEF was new to the French theater of war, they trained hard for several months in preparation of fighting against the German armies. The use by the British of tanks at the Battle of Cambrai in 1917 impressed General Pershing so much that he ordered the creation of a tank force to support the AEF's infantry. As a result, by September 1918, Colonel George S. Patton Jr. had finished training two tank battalions - 144 French-built Renault FT light tanks organized as the 344th and 345th battalions of the United States Tank Corps - at Langres, France for an upcoming offensive at the St. Mihiel salient. In addition to the AEF tanks, the attack was supported by a further 275 French tanks (216 FTs and 59 Schneider CA1 medium tanks) of the French 1st Assault Artillery Brigade; a total of 419 tanks.

Battle
The St. Mihiel offensive began on 12 September with a threefold assault on the salient. The main attack was made against the south face by two American corps. On the right was the I Corps (from right to left the 82d, 90th, 5th, and 2d Divisions in line with the 78th in reserve) covering a front from Pont-à-Mousson on the Moselle westward to Limey; on the left, the IV Corps (from right to left the 89th, 42d, and 1st Divisions in line with the 3rd in reserve) extending along a front from Limey westward to Marvoisin. A secondary thrust was carried out against the west face along the heights of the Meuse, from Mouilly north to Haudimont, by the V Corps (from right to left the 26th Division, the French 15th Colonial Division, and the 8th Brigade, 4th Division in line with the rest of the 4th in reserve). A holding attack against the apex, to keep the enemy in the salient, was made by the French II Colonial Corps (from right to left the French 39th Colonial Division, the French 26th Division, and the French 2d Cavalry Division in line). In First Army reserve were the American 35th, 80th, and 91st Divisions. The Allies also mobilized 1,481 aircraft to provide air superiority and close air support over the front.

Defending the salient was German "Army Detachment C", consisting of eight divisions and a brigade in the line and about two divisions in reserve. The Germans, now desperately short of manpower, had begun a step-by-step withdrawal from the salient only the day before the offensive began. The attack went so well on 12 September that Pershing ordered a speedup in the offensive. By the morning of 13 September the 1st Division, advancing from the east, joined hands with the 26th Division, moving in from the west, and before evening all objectives in the salient had been captured. At this point Pershing halted further advances so that American units could be withdrawn for the coming offensive in the Meuse-Argonne sector.

Order of Battle, First Army, 12 September 1918

 * Section source: OAFH

First Army (United States) - Gen. John J Pershing
 * I Corps: Maj Gen Hunter Liggett
 * Headquarters Observation Group
 * 2nd Balloon Company
 * 5th Balloon Company
 * 82nd Division - Maj Gen William P Burnham
 * 50th Aero Squadron (split duty)
 * 42nd Balloon Company (split duty)
 * 90th Division - Maj Gen Henry T Allen
 * 50th Aero Squadron (split duty)
 * 42nd Balloon Company (split duty
 * 5th Division - Maj Gen John E McMahon
 * 12th Aero Squadron
 * 1st Balloon Company
 * 2nd Division - Maj Gen John A Lejeune
 * 1st Aero Squadron
 * 1st Balloon Company
 * 78th Division (Corps Reserve) - Maj Gen James H McRae
 * IV Corps - Maj Gen Joseph T Dickman
 * Headquarters Observation Group
 * 69th Balloon Company
 * 89th Division - Maj Gen William M Wright
 * 135th Aero Squadron
 * 43rd Balloon Company
 * 42nd Division - Maj Gen Charles T Menoher
 * 90th Aero Squadron
 * 3rd Balloon Company
 * 1st Division - Maj Gen Chales P Summerall
 * 8th Aero Squadron
 * 9th Balloon Company
 * 3rd Division (Corps Reserve) - Maj Gen Beaumont B Buck
 * V Corps - Maj Gen George H Cameron
 * Headquarters Observation Group
 * 99th Aero Squadron
 * 7th Balloon Company
 * 26th Division - Maj Gen Clarence R Edwards
 * 88th Aero Squadron
 * 104th Aero Squadron
 * 6th Balloon Company
 * 15th Colonial Division (French)
 * 8th Balloon Company
 * 4th Division - Maj Gen John L Hines
 * 8th Brigade
 * 4th Field Artillery Brigade
 * remainder of Div in reserve
 * 12th Balloon Company
 * US Army Reserve
 * 35th Division - Maj Gen Peter E Traub
 * 80th Division - Maj Gen Adelbert Cronkhite
 * 91st Division - Maj Gen William H Johnston

List of American Balloon Squadrons
 * Note

Aftermath
General Pershing's operational planning of St. Mihiel separated the salient into several sectors. Each Corps had an assigned sector, by boundaries, that it could operate within. The American V Corps location was at the northwestern vertices, the II French Colonial Corps at the southern apex, and the American IV and I Corps at the south-eastern vertices of the salient. Furthermore, General Pershing's intent was obvious; to envelope the salient by using the main enveloping thrusts of the attack against the weak vertices. The remaining forces would then advance on a broad front toward the direction of Metz. This pincer action, by the IV and V Corps, was to drive the attack into the salient and to link the friendly forces at the French village of Vigneulles, while the II French Colonial Corps kept the remaining Germans tied down.

One reason for the American forces' success at St. Mihiel was General Pershing's thoroughly detailed operations order. Pershing's operation included detailed plans for penetrating the Germans' trenches, using a combined arms approach to warfare. His plan had tanks supporting the advancing infantry, with two tank companies interspersed into a depth of at least three lines, and a third tank company in reserve. The result of the detailed planning was an almost unopposed assault into the salient. The American I Corps reached its first day's objective before noon, and the second day's objective by late afternoon of the second.

Another reason for the American success was the audacity of the small unit commanders on the battlefield. Unlike other officers that commanded their soldiers from the rear, Colonel Patton and his subordinates would lead their men from the front lines. They believed that a commander's personal control of the situation would help ease the chaos of the battlefield.