The First Battle of the Marne began on September 6, 1914. An important Allied victory, it was one of the most decisive battles in history and inaugurated the start of trench warfare that would last for much of the war.
In August 1914, the Germans invaded neutral Belgium and marched toward Paris, France. Along the way, they defeated French armies at the Battles of the Frontiers at Lorraine, Ardennes, Charleroi, and Mons. The French government grew anxious that the German army would reach and take the capital city of Paris by September 5. The city’s military governor, General Joseph-Simon Gallieni, convinced the French commander in chief to save the 6th Army from the front and allow them to defend the city.
By September 1914, the Germans had pushed the French and British forces to within 30 miles of Paris. But as a consequence of advancing rapidly, the Germans had outrun their supply lines and heavy artillery. The Allies took advantage of their enemy’s troubles.
The French had used air reconnaissance and intercepted German radio transmissions to determine the location and state of their opponents. They realized the German 1st Army had crossed the Marne River, disobeying orders from chief of the German general staff, Helmuth von Moltke. This separated the unit from the rest of the army.
Gallieni saw this as an opportunity for his newly formed Army of Paris to attack. The French Army was additionally supported by members of the British Expeditionary Force (BEF). The battle began on September 6, with 150,000 French soldiers in the 6th Army attacking the German 1st Army’s right flank. The 1st German Army had turned to meet the attack, leaving a 30-mile gap between them and the 2nd Army. The combined French and British assault filled the gap and attacked the German 2nd Army.
Heavy fighting occurred in the marshes of Saint Gond, when the Germans repeatedly attacked the French 9th Army. On September 7, a force of more than 6,000 reinforcements were rushed to the front lines using Paris’s taxis and buses. This was the first use of motorized transports during any war, and the cabs were later called the “taxis of the Marne.”
The reinforcements helped turn the tide of the battle. On the 10th, von Moltke ordered his forces to regroup to the northwest, but the French pursued them toward the Aisne River. This time, the Germans built defenses the Allies could not penetrate. Each side tried to outflank its opponents in a series of maneuvers known as the “race to the sea.” This was the beginning of the trench warfare that would continue for four more years.
The Battle of the Marne was a decisive victory for the Allies. It stopped the German advance and led to the end of their two-front war strategy. It also changed the opinion of many people on both sides of the conflict about the length of the war. When World War I began, the popular belief was it would be a short war. This battle and the subsequent development into trench warfare proved otherwise. Political leaders and military commanders now realized this would be an extended struggle.