The Second Battle of the Marne: The Decisive Turn in the First World War

The Second Battle of the Marne, fought in July and August of 1918, marked the decisive turning point of the First World War. Germany's final major offensive of the conflict, part of its Spring Offensive, was not only halted but decisively thrown back by a powerful Allied counterattack. With a massive influx of fresh American troops and hundreds of new tanks, an international Allied force—composed of French, British, American, Italian, Canadian, and Australian units—forced the German army into a permanent retreat from which it never recovered.

By mid-1918, the German army had exhausted itself in a series of five major attacks known collectively as the German Spring Offensive. The goal of Germany's commander, General Erich von Ludendorff, was to break the stalemate of trench warfare before the full force of the arriving American army could be felt. The fifth and final push of this campaign, known as the Marne Offensive, aimed to capture territory east of Paris around the River Marne. This was the same region where the war's first major battle, the 1914 First Battle of the Marne (the "Miracle of the Marne"), had halted an earlier German advance.

Initially, the Germans achieved significant gains. They established a deep bridgehead, or secured foothold, across the Marne River. However, their progress was decisively stopped on July 17. Despite this military setback, the German high command, including Kaiser Wilhelm II, continued to ignore the grim realities at the front. Meeting in early July, they approved new plans for economic mobilization and authorized one more offensive to seize key resource areas.

Ludendorff's plan involved attacks by multiple German armies east and west of the city of Reims. The attack east of Reims, launched on July 15 along a 26-mile front, was a total failure. It was blocked on the first day by the French First Army under General Henri Gouraud. Gouraud's tactics of "defense in depth," rather than holding a single thin line, proved highly effective against the German assault.

Despite the initial successes of the Spring Offensive, the campaign as a whole had failed because the German Army met stiff resistance but could not resupply its men with food or material, since it did not have sufficient transport. Germany had worn down its best troops because it did not adopt the rotation method of the Allies, where soldiers did not permanently fight at the most ferocious points of the front. In addition, the senior German generals had not, unlike their counterparts amongst the Allies, seen the potential of modern weapons, like the tank, or the benefits of all-arms deployment (artillery, infantry, and air support).

Meanwhile, west of Reims, the German Seventh and Ninth Armies achieved better results. They advanced along a 22-mile front, pushed back the French Sixth Army, and successfully crossed the Marne River. Yet, even this success was short-lived. Their advance was also halted by July 17, this time by the French Ninth Army supported by British, Italian, and American troops.

The broader Spring Offensive had ultimately failed. The German army, while initially successful, could not sustain its advances. It faced stiff resistance and suffered from severe logistical problems, unable to adequately resupply its frontline troops. Furthermore, Germany had worn down its best soldiers through constant use, unlike the Allies who rotated their units. German generals also failed to fully appreciate new military technologies, such as the tank, and the benefits of coordinating infantry, artillery, and air power.

Ludendorff's offensives had cost Germany approximately 800,000 casualties without securing any lasting strategic advantage. By August 1918, the United States had 1.4 million soldiers in France, with 250,000 more arriving every month. Germany, in stark contrast, had no reserves left to call upon. All eligible men were already conscripted. Ludendorff's gamble had failed; the war could no longer be won, and German strategy shifted to delaying defeat to secure better peace terms.

German morale plummeted. Mutiny was a real threat, and officers struggled to maintain discipline. Soldiers, suffering from poor rations, were also ravaged by the Spanish influenza pandemic, which hit German lines weeks before the Allies. In June alone, the flu removed 500,000 German soldiers from the front. Poor nutrition made these troops more vulnerable to the virus, further crippling their combat effectiveness.

The morale of those German soldiers left in the field was extremely low, and mutiny was in the air. Already, German officers had struggled to keep their men from simply downing their weapons and feasting on any Allied supplies they came across. Another blow to German morale besides poor rations was the spread of Spanish influenza. The 1918 flu pandemic hit the German lines a few weeks before the Allies, and in June, it removed 500,000 soldiers from the front lines, seriously affecting the fighting capabilities of 13 divisions. Indeed, these two problems were related, since the German soldiers' poorer diet meant that their resistance to the virus was much lower than that of soldiers in the Allied armies.

The Allies, under the unified command of French Marshal Ferdinand Foch, recognized an opportunity. They believed a powerful counterblow could force a German collapse. On July 18, Foch launched a massive counteroffensive—the second phase of the Second Battle of the Marne. French, British, American, Italian, and British Empire divisions attacked the large German bulge, or salient, around the Marne.

The French Tenth Army, led by the aggressive General Charles Mangin, struck the western flank of the salient. The other sides were attacked by the French Sixth Army. The spearhead of the assault was formed by the US First and Second Divisions. These fresh American troops fought with great intensity. As historian John Keegan noted, they displayed "a disregard for casualties scarcely seen on the Western Front since the beginning of the war."

The Allies enjoyed overwhelming advantages. They committed 750 tanks to the battle, including the latest light Renault models. In the air, Allied aircraft outnumbered German planes by a ratio of five to one. These planes identified German artillery positions and strongpoints while preventing the German air force from doing the same. Even in artillery, a traditional German strength, the Allies now held a two-to-one numerical advantage. They employed a devastating "creeping barrage," where a wall of artillery fire moved steadily forward just ahead of the advancing infantry.

Within two days, the Allies advanced 5 to 6 miles. From the west, more French armies joined the attack. The Germans were forced into a full retreat from the Marne salient. The key city of Soissons was recaptured by the Allies on August 4, along with 35,000 German prisoners and 700 artillery pieces. The Germans fell back to a new defensive line along the Aisne and Vesle Rivers.

Another 14 Allied divisions provided support, and perhaps most importantly of all, the Allies could throw at the enemy 750 tanks (including the latest light Renault tanks). They also had domination of the air, Allied aircraft outnumbering German by 5:1. Aircraft were used to identify German artillery positions and points of strongest defence. Allied fighters ensured that the German air force could not provide the same service for their commanders on the ground. Finally, even in artillery, an area where the German Army had traditionally enjoyed numerical superiority, they could only bring half the number the Allies brought to the fight. The Allies used their artillery to create a 'creeping barrage' which was kept up constantly as the infantry advanced behind the falling shells, which were progressively fired further and further forward. The artillery component of the attack was intense, firing "one heavy [shell] per 1.27 yards of ground, and three field artillery shells per yard" (Strachan, 280).

The fighting at the Marne was costly, resulting in approximately 95,000 French and 168,000 German casualties (including prisoners). With his forces depleted, Ludendorff was forced to abandon any further offensive plans. The German army now struggled just to hold its final defensive positions, known as the Hindenburg Line. To man these fortifications, 70,000 wounded soldiers were sent back to the front, and weakened divisions were disbanded to reinforce others.

The Second Battle of the Marne initiated the final, irreversible phase of the war. From this point forward, the German army was steadily pushed back toward its own borders. This period, beginning with the Battle of Amiens in August, is often called the Allied Hundred Days Offensive.

Learning from Ludendorff's errors, Marshal Foch avoided reckless advances that created vulnerable salients. Instead, the Allies advanced methodically, ensuring their artillery and supplies kept pace with the infantry. At Amiens, a combined force of French, British, and Canadian divisions, supported by 435 tanks, achieved a stunning breakthrough. Within 48 hours, they captured 30,000 German prisoners as morale in many German units completely collapsed. Ludendorff called the defeat at Amiens the "black day of the German army."

Henceforth, the German Army would be steadily pushed back towards Germany, starting with the battle of Amiens, the beginning of what is often called the Allied Hundred Days Offensive. Here, Foch did not make Ludendorff's mistake and allow commanders in the field to be lured into extravagant advances to take advantage of pockets of enemy weakness that only resulted in the creation of vulnerable salients held by exhausted troops. Rather, the Allies moved forward much more cautiously, always waiting for the artillery to catch up and aid the infantry.

Germany had no answer to the Allies' numerical superiority and their effective combined use of tanks, aircraft, artillery, and infantry. As unrest spread within the German military and on the home front, the war rapidly concluded. An armistice was signed in November 1918, ending the First World War. The Second Battle of the Marne had proven to be the long-awaited strategic turning point that set this final victory in motion.