Battle of the Frontiers

In accordance with the Schlieffen Plan, the German army wheeled through Belgium during the first three weeks of the First World War. By 14 August, the seven German armies had made contact with the French, who were advancing northwards in accordance with Plan XVII, their own guidelines for offensive action in the event of war. The latter involved an immediate attack through Alsace-Lorraine, which had been held by the Germans since 1870. The Allied forces – which consisted of five French armies and one British – were numerically inferior, particularly in the west. The opposing armies were engaged in four separate, but related battles along the frontiers of France, extending from the Swiss border to Mons in Belgium.

In the Battle of Lorraine, on the eastern end of the Front the French First (Dubail) and Second Armies (Castelnau) crossed the frontier into Germany on 14 August; they advanced towards Sarrebourg and Morhange. The defending German armies – the Sixth. (Crown Prince Rupprecht) and Seventh (von Heeringhen) – a total of 25 divisions, delayed counter-attacking until the enemy had advanced further. The Germans wanted to make it difficult for the French to extricate themselves quickly and go the assistance of their forces further north.When there were indications that the French did infact intend to withdraw, the Germans mounted a converging counter-attack, on 20 August, defeating their opponents at Morhange. Foch’s XX Corps performed with distinction during the battle, which cost the French 20,000 men and 150 guns. As they fell back to the border a new line was established along the Moselle, with the Germans failing to take Nancy.

To the west of Metz, the French Third (Ruffey) and Fourth Armies (Langle de Cary) advanced northwards on 21 August, a day after the German counteroffensive in Lorraine had begun. The aim was to attack the German centre in the flank as it passed through the thickly wooded hills of the Ardennes. In thick fog, they engaged two German Armies – the Fifth Army(Crown Prince Frederick William) and the Fourth (Albrecht, Duke of Württemberg) – which were the pivot of the Schlieffen Plan. For a while the Germans were in a critical situation, but the outnumbered French eventually withdrew after a series of strongly contested actions spread over four days.

During the heavy fighting the French had suffered particularly from German superiority in field and heavy weapons. The Third Army moved back across the Meuse to Verdun, where its commander, Ruffey, was removed. His replacement, Maurice Sarrail, was able to hold on to Verdun. The French Fourth Army withdrew to Stenay and Sedan, where, on 26-28 August, it engaged and temporarily halted the pursuing Germans.

On the same day as the French had attacked in the Ardennes, the German Second Army (Bülow), further to the west, had forced two crossings of the River Sambre between Namur and Charleroi. Some troops were left behind to besiege the fortress of Namur, which fell on 25 August. To Bülow’s left was the German Third Army (Max von Hausen), which had taken Dinant on 15 August. It soon threatened the right flank of the French Fifth Army (Lanrezac), which had moved forward into the Sambre-Meuse area to meet an enemy thrust that was much further west than pre-war French planners had expected. Lanrezac’s position weakened as the French Fourth Army on his right fell back. His forces, which constituted the French left wing, defended Charleroi strongly, but they were attacked on the front and the right. The latter recieved a blow from the German Third Army, which crosses the Meuse and was now striking westwards. With the northern frontier open, Lanrezac was forced to retreat rapidly on 24 August, suffering heavy losses. He counter-attacked towards Guise on 29 August, briefly checking Bülow’s advance along the Oise River.

Lanrezac’s retreat quickly forced the hand of the newly arrived British Expeditionary Force (Sir John French) on the extreme left of the Allied line. The four divisions (70,000 men) had been moving into position behind the canal at Mons when the German First Army (Kluck) attacked on 23 August. More than double the size of the British force, it was delayed for nine hours by the rapid, accurate fire of professional soldiers, There were relatively few casualties on the British side. Plans to withdraw to a new, more defensible position 2½ miles south of the town were abandoned when the British learnt of the French withdrawal from Charleroi. Rapidly pursued by the Germans, I Corps, BEF, was forced to fight a rearguard action at Le Cateau.

Both sides suffered heavy losses in this massive battle which was an overwhelming German success. The French army’s offensive action had failed and 300,000 casualties, a quarter of its combatants, had been sustained. The Germans lost a similar number. The frontier was breached at every point and the Germans moved southwards in accordance with the Schlieffen Plan, ensuring that the decisive battles of the war would be fought on French territory.

Yet the situation for the Allies was far from hopeless. The French army had not collapsed and morale remained high. While the First and Second Armies held the eastern pivot of the line, from Nancy to Verdun, the Third, Fourth and Fifth Armies withdrew southwards in good order, giving Joffre time to regroup his forces and plan the counter-attack that was to be mounted at the Marne. Partly because of poor communications, the German High Command had overestimated the extent of its success and had reduced the strength of the critical right wing prematurely as it marched through France, moving some units to the Eastern Front.