First Battle of the Marne

Background

Germany went to war in August 1914 with a plan to beat France in about six weeks: a great wheel of its right-wing armies through Belgium and round Paris. France's own Plan XVII sent its armies into Alsace and Lorraine, and the Battles of the Frontiers went badly for them. Joffre, the French commander-in-chief, abandoned the offensive, swung his centre and left back with Verdun as the pivot, and began forming a new Sixth Army on his left, drawing troops from his right. The French and British armies fell back in the Great Retreat.

The German right was weakening as it advanced. Moltke, the chief of the General Staff, detached seven regular divisions to invest Maubeuge and Givet and to watch Antwerp, and on 25 August sent four more to East Prussia. The armies outran their supplies, and Moltke's headquarters lost touch with them. After Lanrezac's counter-attack at Guise on 29 August, Bülow's Second Army asked Kluck's First Army to wheel inward, and Moltke approved. Instead of sweeping round the far side of Paris, Kluck now passed east of it and crossed the Marne on 3 September, about 60 km east of the capital. On 4 September Moltke formally gave up the wide sweep.

Gallieni, the military governor of Paris, saw on 3 September what Kluck's turn meant: an open flank on the Ourcq. He readied Maunoury's Sixth Army to strike it and on 4 September won Joffre's agreement. Joffre ordered his whole left to turn about and attack on 6 September.

The armies

Herwig's figures, as English Wikipedia gives them, are about 980,000 French and 100,000 British troops with some 3,000 guns, against about 750,000 Germans with 3,300. French Wikipedia counts 64 French and 6 British divisions against 51 German. Either way the Allies had more men, and in the gap between the German First and Second Armies the BEF outnumbered the Germans roughly ten to one.

From west to east the French had Maunoury's Sixth Army, about 150,000 men and mostly reservists, north-east of Paris; then Sir John French's BEF; Franchet d'Espèrey's Fifth Army; Foch's new Ninth Army by the Marshes of St Gond; de Langle de Cary's Fourth Army around Vitry-le-François; and Sarrail's Third Army west of Verdun. Facing them were Kluck's First, Bülow's Second, Hausen's Third, Duke Albrecht of Württemberg's Fourth and the Crown Prince's Fifth Armies.

Command was the real difference. Joffre kept close watch on his armies, sacked commanders who failed, and his grip tightened as he fell back towards Paris. Moltke stayed far back at Luxembourg with poor communications, and the further his armies advanced the less he controlled them; DiNardo's review of Herwig puts it as each army commander fighting his own war. The German troops were tired from a month of marching: Kluck's men had covered 25 miles a day and more, outrun their convoys and were short of bread and artillery ammunition.

The battle

The Ourcq (5–9 September). On 5 September, a day before Joffre's general offensive, part of Maunoury's Sixth Army moved east from Paris and ran into Gronau's IV Reserve Corps, guarding Kluck's flank, around Monthyon from about midday. This is CDB90's Ourcq I (270). Gronau held for a day and then fell back, and his warning made Kluck turn. Over the next days Kluck drew off first part and then the rest of his army to his threatened flank, winning a temporary advantage over Maunoury: CDB90's Ourcq II (271), coded a draw. Gallieni fed Maunoury what Paris had. On the night of 7–8 September about 600 requisitioned Paris taxis carried part of the 7th Division, newly arrived by rail, towards Nanteuil-le-Haudouin, on the French left. On 8 September the German IV Corps attacked that wing and the French left was bent back between Bouillancy and Nanteuil; that evening Kluck told Moltke the decision would come next day.

The gap and the Morins (6–9 September). Kluck's shift opened a gap of 30 to 50 km between the First and Second Armies, covered only by cavalry. Into it came the BEF and the left of Franchet d'Espèrey's Fifth Army. The BEF was slow: on 6 September it finished 12 km short of its objectives. On 7 September Bülow drew his right back 15 km to the Petit Morin, and on 8 September the Fifth Army's surprise night attack widened the gap: CDB90's Petit Morin (272). The BEF crossed the Petit Morin on 8 September, taking its first large haul of prisoners, though broken bridges held it at La Ferté-sous-Jouarre; on the morning of 9 September its 1st and 2nd Corps crossed the Marne at Charly, Nanteuil and other points. CDB90 treats the BEF's advance against Kluck's screen as Two Morins (273).

St Gond (6–9 September). Bülow's left and Hausen's Saxons struck Foch's Ninth Army along the marshes near Sézanne. On 8 September Hausen attacked at night without a bombardment, pushing Foch back 13 km at a cost of about 11,000 men before stalling. On 9 September the château of Mondement was lost and retaken that evening by the 77th Infantry Regiment. This is CDB90's Marshes of St Gond (274), a German attack that failed.

Vitry and Revigny (6–11 September). Further east the Germans attacked too. Around Vitry-le-François, CDB90's Vitry-le-François (275), the German Fourth Army took the town and drove the French right back past Sermaize, but de Langle held with corps brought from Lorraine and the Vosges; Duke Albrecht left Vitry at noon on 11 September. At the Gap of Revigny (276) the Crown Prince aimed for Bar-le-Duc and the gap between the Fourth and Third Armies, and took Revigny on 6 September. Sarrail held, while behind him Fort Troyon on the Meuse, about 450 men under heavy bombardment from 7 September, kept the river closed.

The decision (8–9 September). Moltke sent Lieutenant-Colonel Hentsch round the armies. On the evening of 8 September Bülow told him the Second Army could not attack. On 9 September, with British columns reported in the gap, Bülow ordered a retreat, and at 11:30 Hentsch told Kluck's chief of staff that the First Army must go back too. On 11 September Moltke ordered the Third, Fourth and Fifth Armies back to the Aisne.

Aftermath

The Germans fell back about 65 km and dug in north of the Aisne. The Allied pursuit was slow, averaging about 19 km a day; the French took 11,717 prisoners, 30 field guns and 100 machine guns, and the British 3,500 prisoners. Losses are hard to separate from the fighting that followed. Herwig counts about 67,700 German, 85,000 French and 1,701 British casualties for the battle itself; broader counts that run on into the rest of September exceed 250,000 for each side.

Moltke was replaced by Falkenhayn on 14 September. The First Battle of the Aisne followed from 13 September, and then the Race to the Sea, at the end of which the Western Front became a trench line. Britannica calls the Marne a strategic but not a tactical German defeat, and blames the Allied failure to exploit it on Maunoury's weak flank attack and the slow advance of the BEF and Fifth Army through the gap. Herwig called it the most important land battle of the twentieth century.

Two stories dominate its memory. The French call it the miracle of the Marne, and the taxis are its emblem; one stands in the Musée de l'Armée. They were real, and the Treasury paid 70,012 francs in fares, but they carried a few thousand men, and Herwig called them militarily insignificant. The other is Hentsch, the staff officer whose order many German officers resented. Herwig's reconstruction of his mission shows that Bülow, not Hentsch, gave the order to retreat.

Wargaming it

The Marne is a battle about a gap and a clock. The whole front, from the Ourcq to Verdun, suits an operational game with divisions or corps as units and half-day turns over 5–12 September. The western half alone, from the Ourcq to the Marshes of St Gond, is a manageable two-player game in which every German move on one flank opens a hole in the other.

The German player's problem is Kluck's: beating Maunoury on the Ourcq means stripping the line facing the BEF. The Allied player's problem is speed. The BEF and the Fifth Army had a 30–50 km gap held only by cavalry and still crept forward. Rivers (the Ourcq, Grand and Petit Morin and the Marne) and their bridges should cost time, and broken bridges more.

Command rules matter more than firepower here. Moltke was out of touch at Luxembourg, and his army commanders acted on their own; a game should make German co-ordination slow and uncertain, perhaps with a random Hentsch event that can force a withdrawal. Reinforcements from Paris, by rail and taxi, should trickle in on the Allied left.

For a tactical scenario, Mondement on 9 September or the IV Reserve Corps' fight around Monthyon on 5 September work at battalion level. For what-ifs: Kluck pressing his attack on 9 September, as he told Moltke he would; Gallieni's preferred blow at Kluck's rear rather than his front; or Fort Troyon falling and opening the Meuse behind Sarrail.

Maps and pictures

Pictures from the time

Photographs by the armies' photographers and the press, and drawings made at the time: free-to-use pictures from the battle's category on Wikimedia Commons. Each opens its file page there, with the full caption and source.