- At 5am, Hentsch has a meeting with two of Bülow's staff officers, the General himself still asleep. The conversation confirms the conclusions of the previous day - 2nd Army can hold only if 1st Army immediately disengages and linked up with the former's western flank; if not, 2nd Army will retreat behind the Marne River. At 6am he departs 2nd Army headquarters for 1st Army.
At 9am, Bülow receives the latest aerial reconnaissance report, which states that numerous columns of enemy forces are north of the Petit Morin moving towards the Marne. For Bülow, the time has come. At 902am he signals a general retreat of 2nd Army. This is the crucial moment, and the crucial decision. Once 2nd Army has begun to retreat, the position of 1st Army is entirely untenable - it will have to retreat to avoid complete encirclement. Bülow's choice, made entirely without any communication with either Moltke at OHL or Kluck at 1st Army, is the effective end of the German offensive in the West.
- Along the Ourcq River the battle between the German 1st Army and the French 6th Army reaches its climax. General Kluck knows that time is running out to defeat the French before the advance of the BEF to the east cuts behind him. At 9am reports are received from German cavalry divisions that British and French units were across the Marne. In response, at 930am Kluck orders II Corps to turn to face southeast to confront the threat from the enemy. Kluck, however, remains convinced that the battle against 6th Army can be still won. He orders IX Corps, his northern-most unit, to attack with all its strength to turn the enemy's flank and force their retreat. As Kluck states to a staff officer: 'Every man must be convinced that the enveloping attack must bring the decision.' The attack of IX Corps shatters the French 61st Reserve Division and is poised to envelop the northern flank of the French 6th Army. To the commander of IX Corps, victory and Paris appear imminent. At that moment a visitor arrives at 1st Army headquarters - Lieutenant Colonel Richard Hentsch.
Hentsch arrives at 1130am after a journey of over five hours on roads clogged by refugees, wrecked vehicles, wounded soldiers, and German cavalry fleeing the supposedly imminent advance of the British and French. His personal experience of the gap between 1st and 2nd armies can hardly have improved the Lieutenant-Colonel's disposition. Hentsch meets with General Hermann von Kuhl, Kluck's Chief of Staff. The commanding general himself is not present, and though he is only a few hundred yards away at his command post neither Kuhl nor Hentsch summon him. The fate of 1st Army is thus decided by two staff officers.
Kuhl begins the meeting with an overview of the current situation, as it appears from 1st Army headquarters. Despite heavy fighting with the French 6th Army, the arrival of IV and IX Corps had stabilized the situation, and that the latter was about to turn the northern flank of the French. Further, he was not concerned by the threat posed by the BEF - after several battles with the British and pursuing them for two weeks, Kuhl was convinced that they were largely shattered and operated too slowly to make a decisive move (the latter opinion, at least, was not without reason).
Kuhl's presentation makes no sense to Hentsch, who with his larger perspective on the battle sees nothing but imminent disaster. He emphasizes the stalemate in Lorraine, and the inability of 5th Army to break through west of Verdun. 2nd Army, meanwhile, has been defeated and is retreating north of the Marne. 1st Army is to retreat in the direction of Soissons to link up with 2nd Army, and the redeployment of part of 7th Army to Saint-Quentin would allow for a resumption of the offensive. When Hentsch draws out 1st Army's line of retreat on a map, Kuhl objects - cannot Hentsch see that they are on the brink of victory? Hentsch's response is that 2nd Army has been reduced to 'cinders', a description that will become notorious in after-the-fact arguments in Germany over the appropriateness of the retreat from the Marne. Finally, Hentsch states that he has the full authority of Moltke to issue orders in his name. Kuhl, having no direct line of communication with OHL at Luxembourg, and confronted with the vision of a broken 2nd Army, has no option but to agree. At 130pm, Kluck, informed by Kuhl of the decision, issues orders to break off the attack on the French and withdraw towards Soissons.
- To the soldiers at the front, the order to retreat comes like a bolt from the blue. They have been on the march for almost month, every day advancing deeper and deeper into France. Where they have met the French or British, they have been victorious. Even in the past few days, most units have held the French counterattack. The order to retreat, then, appears to be snatching defeat from the jaws of victory. When General Oskar von Hutier, commander of the 1st Guards Division in 2nd Army, is informed of the retreat, his reply reflects the opinion of many: 'Have they all gone crazy?'
- At OHL, Moltke, remaining largely in the dark regarding the state of operations, is chronically pessimistic. To his wife he writes: 'It goes badly. The battles east of Paris will not end in our favour . . . . and we certainly will be made to pay for all that has been destroyed.' When news comes in of Bülow's order to retreat, Moltke voices no opposition, though it means the end of the great German offensive into France. Wilhelm II, present at OHL, is vehemently opposed to the retreat, and argues passionately with Moltke. According to the staff officers present, Moltke's nerves have been shattered, just as they had been on August 1st. Minister of War Falkenhayn notes in his diary today: 'Our General Staff has totally lost their heads. Schlieffen's notes have come to an end and therewith Moltke's wit.' The argument between the Kaiser and Moltke is immaterial anyway - even if they wanted to stop the retreat, they lack any means of communication to order Bülow and Kluck to stand and fight.
- By the middle of the afternoon, both the BEF and the French 5th Army have crossed the Marne, and by the evening it becomes clear to Joffre that the Germans on his left are in retreat. He issues instructions for 5th and 6th armies, plus the BEF, to pursue the enemy and attempt an envelopment of the German 1st Army. To the Minister of War in Bordeaux Joffre cables a reassuring note that, while unwilling to claim yet a decisive victory, assures the government that the situation is satisfactory and promising.
- The retreat of the German 1st and 2nd armies today brings an end to the Battle of the Marne, and indeed the first phase of the war on the Western Front. Over two million soldiers have fought along the front line, and while estimates vary, it is believed that a quarter of a million Germans and a quarter of a million Frenchmen are casualties, a ratio of one in four combatants. On a per-day basis, it is the bloodiest battle of the war on the Western Front.
The Battle of the Marne is one of the most decisive in human history, for two reasons. First, the Germans had staked all on a rapid invasion and defeat of France before Russia could deploy its full weight against them. For years the German army had been focused on this one mission - war games simulated various permutations of the advance, logistics officers poured over road maps of Belgium and northern France, the mobilization plan tweaked and retweaked down to the minute to ensure the Germans had every advantage of time. By today, the 39th day since German mobilization, the French were to have been crushed. Instead, it is the Germans who have been defeated. The sense of shock and disbelief among the officers of the German army can hardly be understated - it had been taken as a fundamental article of faith that the German army was inherently superior to the French army, and many simply cannot conceive of a world in which that is not true. Hence the almost immediate search for scapegoats, for an internal reason for their defeat. Had Moltke botched the plan? Had Hentsch exceeded his authority? Was Bülow over-cautious? Was Kluck's 'inward turn' the fundamental mistake? What all these questions ignore is the basic truth that not only had the Germans lost, but the French had won. In particular, Joseph Joffre had achieved a victory that almost looked impossible two weeks earlier in the aftermath of the disastrous Battle of the Frontiers. His ability to recover from the failure of pre-war planning cannot be understated (and stands in sharp contrast to Moltke's reactions as his pre-war plans collapsed) - without his recognition of the changed circumstances after August 24th and his immediate redeployment of forces from his left to his right, France surely would have been lost. Whatever else can be blamed on Joffre - and in the years to come there is much he can be blamed for - his service in the last week of August and the first week of September ensured the survival of the French republic. Credit must also be given to the French soldier - undertaking a constant retreat under enemy fire for two weeks, and then to turn and defeat said enemy, is one of the great feats of modern arms. Finally, there is the BEF. For all that Sir John French can be justly criticized for his pessimism, and the British slowness in movement, and indeed simply the minuscule size of the BEF in comparison to the armies of France and Germany, at the crucial moment it found itself largely by coincidence at the most important point on the front, and in advancing played a role out of all proportion to its size.
The second reason the Battle of the Marne is decisive is precisely that it is not decisive. The German army is defeated, but it is not destroyed. 1st and 2nd armies have suffered, but they are retreating in relatively good order, escaping the potential threat of encirclement. All sides had expected the first couple of months to see one or two climactic battles, after which one army would be destroyed and that side compelled to surrender. The climactic battles have occurred - the Battle of the Marne, as with the Battle of the Frontiers and indeed the battles in East Prussia and Galicia, have been among the largest in history - but the losing side has not been compelled to surrender. Indeed, the German expectation at the end of September 9th is that a brief retreat will be followed by a resumption of the offensive. The true legacy of the Marne is that it ensures that the war will not end in a quick victory by either side, but will continue. The Marne was not the end, but rather the beginning, of the war, the likes of which had hardly been imagined before the great armies took the field a month ago.
- Elsewhere on the Western Front today, the German 4th Army, in an attempt to emulate the partial success of 3rd Army yesterday, launches a morning bayonet charge on French artillery positions belonging to the French 4th Army. Its commander Duke Albrecht orders a lengthy artillery barrage to precede the attack, which gives the French ample warning. When the Germans advanced, they encounter active and vigorous resistance, and fail to accomplish anything. By 1030pm, the commander of the French 4th Army is able to inform Joffre that his position is secure.
- The Belgian army in the fortifications of Antwerp today sorties, in an effort to disrupt German lines of communication and force the Germans to keep additional forces in Belgium as opposed to on the front lines.
- Even as the great German offensive in the west is collapsing today, German Chancellor Theodor von Bethmann-Hollweg has drafted today a list of German aims. Designed to indicate the lines on which German negotiators should proceed after a quick victory over France, the September Programme, as it comes to be known, is nothing if not ambitious. Parts of Belgium, including Antwerp, were to be directly annexed to Germany, while the rest would become a client state. France would cede the vital industrial region of Longwy-Briey, and possible some of its Channel ports, to Germany. Luxembourg would also be annexed to Germany. To the east Russia was to be weakened through granting self-determination to minorities like the Poles, who would in turn become client states of Germany (this was preferably than directly annexing Russian territory - the last thing the Germans wanted was more Poles in their country). All of central Europe - Mitteleuropa - was to be united in a vast economic union, to operate for German benefit. All of central Africa was to be acquired, taking colonies from Britain, France, Portugal, and Belgium to form Mittelafrika. Coaling stations would also be acquired around the world to give the German navy a global reach.
These war aims are designed to secure permanent German hegemony in Europe and a secure place as a global power. As such, they are entirely unacceptable to the Entente - British policy for centuries had been to keep the ports of the Low Countries out of hostile hands - and could only have been achieved through an absolute and crushing victory that would allow the Germans to impose its terms on its enemies. The irony of the September Programme being drafted on the day the Germans begin their retreat from the Marne hardly needs stating.
- In East Prussia this morning General François' I Corps launches an attack on the far southern flank of the Russian 1st Army, where the latter is supported by elements of the newly-forming Russian 10th Army. Once again, with the rest of 8th Army stymied by the Russians, it is I Corps that makes the decisive breakthrough - they shatter Russian units southeast of Lötzen and begin to drive against the flank of the Russian forces holding up Mackensen's XVII Corps at Lötzen. As a result of the breakthrough I Corps takes thirty thousand prisoners and captures sixty artillery pieces. The commander of the Russian 10th Army refuses to send reinforcements, as he does not want his army to be exhausted through piecemeal contributions to the front. With the southern flank shattered, disaster now threatens to overtake the Russian 1st Army just as it had overtaken the Russian 2nd Army. However, General Rennenkampf of 1st Army, whatever his other faults, is not as foolish as to continue to advance in the centre while his flanks are turned - this evening he orders the Russian 1st Army to retreat.
- The right flank of the Austro-Hungarian 1st Army is defeated today by the Russian 4th Army, while two corps belonging to the Russian 5th Army have advanced to threaten the Austro-Hungarian line of retreat. Faced with the prospect of imminent encirclement and destruction, the commander of 1st Army orders a retreat behind the San River.
To the south, the Austro-Hungarian 2nd Army has achieved some tactical successes against the Russian 8th Army. Though the Russians are able to withdraw in good order and establish new defensive lines, the local victories convince Conrad that his grand scheme to envelop the two Russian armies in the south is still viable, despite the tide of news from elsewhere on the battlefield.
- The German East Asiatic Squadron departs Christmas Island today, sailing southwest for Samoa.