Battle of Lorraine, 1914: Plan XVII marches into a trap

For the French, Lorraine was more than a border. Alsace and most of Lorraine had been German since the Franco-Prussian War of 1871, and recovering them was the great aim of French policy. Plan XVII, France's war plan, massed most of the army in the center and south and called for an immediate offensive across the border. John Rickard of HistoryOfWar.org lists the reasons: the lost provinces, the hope of relieving Russia while its huge army mobilized, and the knowledge that France would only grow more outnumbered as time went on.²

General Joseph Joffre, the French commander, also misread the enemy. David T. Zabecki writes in HistoryNet that Joffre did not believe Germany would put its reservists into the front line at once, and so concluded that it lacked the men for a great sweep through Belgium. That sweep was exactly what the German plan intended. In the south the Germans meant to give ground, so that every mile the French advanced into Lorraine took them further from the decisive battle in the north.³

Four days of easy advance

A first French attack into southern Alsace had taken Mulhouse on 7 August and lost it three days later. On 14 August the main offensive began. General Auguste Dubail's First Army crossed into southern Lorraine towards Sarrebourg, and General Édouard de Castelnau's Second Army, to the north, advanced on Morhange. They believed they faced six German corps at most; HistoryNet says they faced nine. Opposing them were the German Sixth Army under Crown Prince Rupprecht of Bavaria and the Seventh under General Josias von Heeringen.⁴

For four days the French met no serious resistance. The Germans kept in contact and pounded the columns with artillery as they toiled over poor roads, but gave way. By 17 or 18 August the French were up to 25 miles inside German territory and had taken Sarrebourg; HistoryOfWar.org credits its capture to the VIII Corps on 18 August, HistoryNet to the First Army a day earlier.⁵

The counterstroke at Sarrebourg and Morhange

The advance had cost the French more than distance. The Germans had far more heavy guns and machine guns than the French, whose field artillery relied almost entirely on the light 75 mm gun, and in the advance the two French armies lost touch with each other. Dubail ordered a night attack on 19 to 20 August to close the gap.⁶

Rupprecht, meanwhile, had argued with German headquarters against further retreat and won permission, or at least was not forbidden, to attack. On 20 August the two sides collided head on. By the afternoon the First Army had been forced out of Sarrebourg, and the Sixth Army turned on the Second Army near Morhange and overwhelmed it. By 22 August de Castelnau's men were back across the Meurthe, where they had started six days earlier; only Foch's XX Corps held its ground. The First Army had to fall back to the same line. The picture at the top of this page, a French magazine illustration of 1915, shows a heroic charge at Morhange; it was in fact a heavy French defeat.⁷

The Grand Couronné and the Charmes Gap

The German plan expected the battle to end there, with the French pinned on the Meurthe. Instead, Rupprecht and Heeringen persuaded the chief of staff, Helmuth von Moltke the Younger, to let them press on. De Castelnau considered giving up the heights of the Grand Couronné in front of Nancy, but Foch protested and Joffre insisted they be held. A French counterattack on 24 August struck the flank of the German advance, and orders from German headquarters to push through the Charmes Gap and cross the Moselle proved impossible to carry out.⁸

The Germans attacked the Grand Couronné on 4 September with a heavy bombardment. By 7 September de Castelnau was again ready to abandon Nancy, and again Joffre refused, as the Battle of the Marne was now raging to the west. On 8 September German headquarters rationed the Sixth Army's artillery ammunition, and the offensive ground to a halt. On 12 September the Germans began to withdraw, and the French followed as far as the Seille, where the front in this sector stayed for the rest of the war.⁹

What Lorraine meant

HistoryNet puts the losses on both sides in the fighting south of Metz, from 7 August to 13 September, at some 350,000 to 400,000 men, in a battle that is now almost forgotten. Rickard notes the irony that the stubborn French defense of the Meurthe line let Joffre take troops from Lorraine and send them to the Marne, among them Foch, who left to command the new Ninth Army.¹⁰

In Germany, Rupprecht was blamed for a while for pressing his own offensive instead of sending troops north. HistoryNet judges that the real responsibility lay with Moltke and his headquarters, which suggested, recommended and changed their minds instead of giving orders. The French learned the harder lesson. Plan XVII's faith in the offensive had cost them dearly in the first weeks of the war, and the line of trenches that formed in Lorraine was among the first signs of what the war would become.¹¹