Paris crackled with panic as September 1914 arrived. Just a month into the Great War, the Germans had the French capital within sight. Sporadic air raids hit the city at night, resulting in damage more psychological than physical, but on September 2 a German biplane carpet-bombed the city with propaganda leaflets that read, “There is nothing you can do but surrender.” As crowds called for their leaders to declare Paris an “open city” in order to spare it from enemy attack, tens of thousands of Parisians thronged rail stations to flee the city. The French government had already bolted earlier that day for Bordeaux, taking the gold from the central bank with it. Workers at the Louvre feverishly shuttled masterworks to Toulouse. The military governor of Paris, General Joseph-Simon Gallieni, predicted the Germans would arrive in the City of Lights by September 5 if no actions were taken.

From the day Germany declared war on France on August 3, the fight had been one-sided. German forces had advanced like lightning through neutral Belgium and the French countryside, and by September 2, German cavalrymen had crossed the Marne River and been spotted on the outskirts of Meaux, only 25 miles northeast of the French capital. It appeared that Germany’s “Schlieffen Plan,” which called for overwhelming the disorganized French army in six weeks before transferring forces to an eastern front against Russia, was working to perfection.

With its army in retreat, the French needed a miracle to save Paris from enemy occupation. They received it on September 3 when French reconnaissance pilots spotted the forces of German General Alexander von Kluck’s First Army, which had been pointed at Paris like a spear tip, suddenly switch to the southeast. Although under orders to support the Second Army to guard against possible attacks from Paris, the aggressive von Kluck instead sought glory and a chance to drive a stake in the enemy by pursuing the retreating French Fifth Army across the Marne River east of Paris. By doing so, his troops, exhausted after weeks of marching and fighting, outran their supply lines, and he inadvertently exposed his right flank to French forces.

The French seized the opportunity, and on September 5 French Commander-in-Chief Joseph Joffre ordered a counterattack between Senlis and Meaux. The following morning, French troops heard the following proclamation: “At the moment when the battle upon which hangs the fate of France is about to begin, all must remember that the time for looking back is past; every effort must be concentrated on attacking and throwing the enemy back.”

General Michel-Joseph Maunoury’s Sixth Army surprised the Germans and struck the right flank of von Kluck’s forces near the Marne River. By turning his army to meet the French, von Kluck created a 30-mile breach between Germany’s First and Second Armies through which the French Fifth Army and British forces poured. The bloody fighting of raged for three days along a 100-mile front.

The first major battle of World War I delivered death on an industrial scale that had not been seen before in warfare. Machine guns and modern cannons mowed down enemy forces. While radio intercepts and aerial reconnaissance used in the battle presaged the future of warfare, echoes of the past remained in the cavalry troops charging on horseback, soldiers in red pantaloons charging behind commanders with swords drawn and drummers providing a musical soundtrack to the battle.

Fresh troops rushed from Paris to the front line thanks to an unlikely means of transport—a taxi. Gallieni requisitioned a fleet of 600 Renault taxis to drive 6,000 soldiers from the capital to the battleground. From their wartime service, the vehicles gained the nickname “Taxi de la Marne.”

The new troops further pushed the Germans back, and on September 9 they began a retreat north of the Aisne River, where the battle came to an eventual close after a week of fighting that claimed upwards of 100,000 lives on both sides. Dubbed the “Miracle of the Marne,” the strategic victory for the Allies proved to be a critical turning point in World War I. Paris had been saved from capture. Notions of a short war had been dashed. The Schlieffen Plan had been torn to tatters.

For the next two months, each side attempted to outflank the other on what became known as the “Race to the Sea.” Both sides literally dug in for a long fight as a network of trenches and barbed wire severed Europe from the North Sea to Switzerland by the end of 1914. Both sides bogged down in a slow, bloody grind of trench warfare that would last until the end of the war in 1918. As awful as the First Battle of the Marne was, it would get worse. Edward Spears, a British Expeditionary Force liaison officer, wrote years later in his memoirs, “I am deeply thankful that none of those who gazed across the Aisne of September 14 had the faintest glimmer of what was awaiting them.”