‘Foch’s Grand Offensive’: the biggest battle you’ve never heard of

Between 26 September and 9 October 1918, the biggest battle ever fought in western Europe took place. Involving more than twice as many men as would fight at Normandy in 1944, the bloody series of concentric attacks on the German lines in France known as ‘Foch’s Grand Offensive’ was decisive in the outcome of the First World War, says historian Jonathan Boff. Writing for History Extra, he explores the events of the Allied offensive and how it pointed the way towards modern warfare…

US soldiers man a machine gun post in the Argonne Forest, during the Meuse-Argonne offensive, 1918. (Photo by US Army Signal Corps/American Stock/Getty Images)

One hundred years ago, the Allied armies* in France and Flanders unleashed the biggest battle ever fought in western Europe. It’s a battle of which few of us may ever have heard, but it (and the Hundred Days Offensive of August and November 1918, of which it was a part) helped decide the outcome of the First World War. Over the course of five days, nearly two million American, Belgian, British and French soldiers climbed out of their trenches and, picking their way between shell bursts and clouds of poison gas, overran German trenches from the River Meuse to the English Channel.

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Within just 48 hours at Ypres, which had long been the site of terrible fighting, the British captured ground that had taken nearly four months of mud-bound agony to seize the previous year. Further south, the Allies stormed the vaunted defences of the Hindenburg Line [the final line of German defences on the western front], shocking the German high command so deeply that it decided to demand an armistice without delay. Peace took another six weeks to come, but its foundations were laid in the fighting known as Foch’s Grand Offensive, which took place between 26 September and 9 October 1918. Yet this battle remains unknown to all bar the most keen of military historians.

c1916: British soldiers sitting around a lamp in their trench. (Photo by Hulton Archive/Getty Images)

Throughout the spring and early summer of 1918, the German army, desperate to end the war before the US Army arrived in strength, had launched repeated hammer blows at the British and French forces on the western front. The Allied line had buckled and been forced back, but crucially it hadn’t broken. The weakened German army was poorly equipped to resist the Allied counterattack which followed. This began on the Marne in July, continued at Amiens on 8 August, and extended across the old battlefields of 1916 and 1917 along much of the front later that month. In heavy and bloody fighting, the Allies pushed the Germans back.

Allied leaders, led by the pugnacious French general Ferdinand Foch, had stumbled across a new and effective operational method: instead of trying to break through enemy lines and drive deep into the rear – an approach which had not succeeded in four years of trying – they now suspended even successful operations after a few days and shifted the point of attack to somewhere else on the line. This saved the attackers’ energy, while sucking in and chewing up German reserves. Under the relentless pressure of this ‘rolling attrition’, in early September the German high command, led by Erich Ludendorff and Paul von Hindenburg, ordered their men to fall back to the positions they had occupied at the beginning of the year, in the formidable defences of the so-called Hindenburg Line. Here, they hoped to hold out until winter forced a pause in the fighting.

The commanders of the French and British forces photographed during 1918. Left to right, General Joseph Joffre, French president Raymond Poincaré, King George V, General Ferdinand Foch, and General Douglas Haig. (Mansell/The LIFE Picture Collection/Getty Images)
The commanders of the French and British forces photographed during 1918. Left to right, General Joseph Joffre, French president Raymond Poincaré, King George V, General Ferdinand Foch, and General Douglas Haig. (Mansell/The LIFE Picture Collection/Getty Images)

Breaching the German lines was going to be no pushover: their positions, perfected by years of siege warfare, were deep and strong. Carefully sited fortifications with overlapping fields of fire, built around concrete pillboxes and dug-outs and protected by belts of barbed wire, stretched back in line after line of defences, often several miles deep. German units might have been starting to run low on infantrymen, but they still had plenty of machine guns and artillery, and the troops’ morale had recovered from the toughhit in the summer. The Allies had every reason to believe that they faced a very tough challenge.

Nonetheless, Foch was determined to give the Germans no respite. Together with the national contingent commanders – Philippe Pétain for France, John ‘Black Jack’ Pershing for the United States, and Sir Douglas Haig for Britain and its empire – Foch began putting together a grand offensive to bounce the Germans out of their defences and liberate France and Belgium. They spent most of September repairing the shattered roads and railways leading up to the new Allied positions, stockpiling matériel, and moving up the men and machines they would need. Foch intended to unleash a flurry of rapid blows up and down 350 kilometres of the western front, from Verdun almost to the English Channel.

A photograph of a crowd in Berlin celebrating Kaiser Wilhelm II of Germany's proclamation of war against Great Britain, August 1914. (Photo by Historica Graphica Collection/Heritage Images/Getty Images)

Operating on such a broad front had the political advantage of balancing out the contribution of each ally, as Eisenhower would find in a later war. Militarily, it also created multiple threats at once, which might both overstretch German reserves and overload the capacity of Ludendorff and his generals to react. In all, on the active front from the River Meuse to the sea, the Allies mustered 171 divisions – probably around 1,750,000 fighting men – supported by artillery guns, tanks and aircraft in their thousands, against about 1,250,000 Germans in 165 divisions.

The western front ablaze

The ‘Grand Offensive’ opened just before dawn on 26 September 1918 with a powerful Franco-American force driving into the Argonne forest and along the left bank of the Meuse in France. The next day, the British Third and First armies crossed the Canal du Nord and drove through the thickest part of the Hindenburg Line toward Cambrai. On Saturday 28 September, French, Belgian and British forces attacked at Ypres. The spotlight returned to the centre on 29 September, where the British Fourth and French First armies stormed over the St Quentin Canal and penetrated deep into the Hindenburg Line, while the River Aisne was the site of a further major French attack on 30 September.

British soldiers attacking the Hindenburg Line, the final line of German defences on the western front, during the First World War. (Photo by The Print Collector/Print Collector/Getty Images)
British soldiers attacking the Hindenburg Line, the final line of German defences on the western front, during the First World War. (Photo by The Print Collector/Print Collector/Getty Images)

Within five days, Foch had set the western front ablaze. The German defenders fought hard: not one of the attacks opened a clean break in the German lines, and progress was often slow. General Pershing suspended his offensive in the Argonne Forest after just three days, for instance, having lost 45,000 men and advanced at best only 12 kilometres, while the British attack on Cambrai stalled. It took several days of bitter fighting to clear the defenders from the Hindenburg Line in the St Quentin area. Only at Ypres did the defence collapse, but even here the Allied advance soon ground to a halt: it was simply too great a task to move supplies across the shattered ground of the salient [a part of battlefield which juts out or bulges into enemy territory].

The beauty of Foch’s plan, however, was that it didn’t depend on achieving a breakthrough at any one point, much less all of them. Instead, it relied on cumulative effect, and it proved spectacularly successful. The evident inability of the German army to hold its ground, even in the strongest trench defences ever constructed, raised alarm throughout the ranks. A captured German non-commissioned officer admitted that “Germany is defeated, and the sooner we recognise it, the better”.

Two members of the Women's Army Auxiliary Corps find another use for discarded helmets in France during the First World War. (Alamy)

Likewise, Crown Prince Rupprecht of Bavaria, the field marshal commanding the defence in northern France, wrote in his diary on 29 September: “We must absolutely make peace: there’s nothing else for it”.

Rupprecht could not yet know it, but at six o’clock the previous night, Ludendorff and Hindenburg had already come to the same conclusion. In his memoirs Ludendorff pretended that it was news of the imminent collapse of Bulgaria, rather than the military situation in the west, which provoked their decision. This was a transparent lie, told to deflect blame away from himself: at the time he told his staff officers that he wanted to save the army from total collapse in case it was needed to suppress a Bolshevik uprising back home. The generals told the Kaiser it was time to approach US president Woodrow Wilson and request a ceasefire. Within a week, a peace note was on its way to Washington. So began a process that soon ran out of the German high command’s control, with far-reaching and disastrous consequences: by the middle of November, the army had disintegrated, an armistice had been signed, and revolutions had swept crowned heads from thrones all over Germany and central Europe.

German generals Paul Von Hindenburg (l) and Erich Ludendorff (r) consider at a map with Kaiser Wilhelm II (centre) during the First World War. (Image by Bettmann / Getty Images)
German generals Paul Von Hindenburg (l) and Erich Ludendorff (r) consider at a map with Kaiser Wilhelm II (centre) during the First World War. (Image by Bettmann / Getty Images)

In the meantime, the offensive ground bloodily on. By about 8 October, the German army was falling back once more. It was soon fighting a semi-mobile war in much more open country, without trench lines to rally on, improvising defences where it could, in one desperate rear-guard action after another. This kind of combat was far from the trench warfare of earlier years, and the German army began to crumble under the pressure. By 5 November it was thoroughly beaten and retreating towards the German frontier as fast as it could march.

The impact of the battle

Casualties during the last phase of the war are hard to calculate, not least because record-keeping was poor. In the ‘Grand Offensive’ itself, British and empire forces alone probably lost nearly 100,000 men, though the total could easily have been as high as a quarter of a million for each side.

The Allied victory was built on weight of numbers, especially in manpower, artillery, tanks and aircraft, as well as on old-fashioned human virtues such as guts and determination. A major contribution, however, was made by the Allies’ ability to out-think their enemy. They had better learnt the lessons of previous years. Experienced commanders now led formations capable of integrating new technologies into combined arms tactics and operational approaches far advanced from those of even 18 months previously. The Germans, quite simply, ran out of responses as their command system seized up under the pressure Foch was exerting.

British 40th Division tanks transporting captured German guns from the battle of Cambrai. (Photo by Underwood Archives/Getty Images)

Foch’s ‘Grand Offensive’ was much more than the battle which, more than any other, doomed Germany to defeat in the First World War. It was also the biggest battle ever fought in western Europe, involving more than twice as many men, and twice as bloody, as, say, the battle for Normandy in 1944. More importantly still, together with the other operations of autumn 1918, it pointed the way to the future of modern warfare. When British and American generals sat down to plan the artillery-intensive, combined arms set-piece attacks of the Second World War, they took their inspiration from the battles they had fought as subalterns in 1918. The ‘Grand Offensive’, along with the other battles of the so-called Hundred Days campaign, established a template that survives today. It is no coincidence that in autumn 2018, officers from the American, Australian, Belgian, British, Canadian, French, German and New Zealand armies will once again meet on the battlefields of 1918, this time as friends, to see what lessons modern armies can learn from the events of 100 years ago.

Why, then, is this battle so little known? A combination of factors are at work. Even at the time, these events were not well reported: partly because self-censoring journalists were being purposely vague about details, and partly because the appetite for military news was waning after four years of war. More recent neglect is perhaps due to the failure of this phase of the war to conform to ‘mud, blood and futility’ stereotypes, a fascination with remembering those who died even at the expense of those who made their sacrifice in other ways and survived, or a desire to avoid anything that might look like celebration, rather than commemoration. We can all agree that there is no place for triumphalism in our history of the First World War. But we should remember the war as it was. The Allied victory won as a result of Foch’s ‘Grand Offensive’ was an important part of that war, and it deserves to be better known.

Dr Jonathan Boff is a senior lecturer in history at the University of Birmingham. His books include Winning and Losing on the Western Front (Cambridge University Press, 2012) and Haig’s Enemy: Crown Prince Rupprecht and the German Army on the Western Front(Oxford University Press, April 2018).

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 *Technically, the United States was an Associated Power, rather than an Ally, of Belgium, Britain and France, but for convenience they will all be referred to here as ‘the Allies’.

To read more about the First World War, click here.