On the evening of September 5, 1914, General Joseph Joffre, commander in chief of the French army during World War I, readies his troops for a renewed offensive against the advancing Germans at the Marne River in northeastern France, set to begin the following morning.

With the French 6th Army poised to begin an attack from its position against the right flank of the German 1st Army to the northeast of Paris, Joffre was under pressure from Paris’ military governor, General Joseph-Simon Gallieni, to launch a general offensive in support of the attack. On September 3, Joffre made the difficult decision to replace the commander of the 5th Army, General Charles Lanrezac, punishing him for his caution in ordering a retreat at the Battle of Charleroi on August 22-24—which had in fact saved the French left wing from envelopment by the Germans—and replacing him with the more aggressive General Louis Franchet d’Esperey.

The French planned for the 5th Army, having crossed the Marne River east of Paris with the Germans in hot pursuit, to launch a coordinated attack with the 6th Army on the two advancing German armies: the 1st, under General Alexander von Kluck, and the 2nd, led by General Karl von Bulow. To ensure the attack’s success, however, the French wanted the support of the British Expeditionary Force (BEF), under the command of Field Marshal Sir John French, who was still coordinating his army’s retreat after its defeat in the Battle of Mons, also on August 24.

At ten o’clock on the night of September 4, Joffre signed the order authorizing the 6th Army’s attack. By the next morning, however, he was still uncertain about the commitment of the British troops. At a meeting later that afternoon, in French’s headquarters, Joffre pleaded with his British counterpart to authorize his troops to join in the attack, promising that the BEF would be supported on either side by the French 5th and 6th Armies. The “supreme moment” had arrived, Joffre insisted, and “the future of Europe” was on the line. “I cannot believe the British Army will refuse to do its share in this supreme crisis….The honor of England is at stake!” After struggling to answer in French, a visibly emotional British commander in chief gave up, reportedly exclaiming to one of his officers: “Damn it, I can’t explain. Tell him that all that men can do, our fellows will do.”

That night, Joffre signed the order proclaiming the attack at the Marne, to be read to his troops the next morning: “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….Under present conditions no weakness can be tolerated.” The decisive four-day-long Battle of the Marne would end in an Allied victory, halting the month-long German advance and sparking a growing recognition on both sides that the war would go on longer than either had anticipated.