Hundred Days Offensive (1918): The Allied Push to Victory

The Hundred Days Offensive was the final campaign of the First World War on the Western Front. Beginning with the Battle of Amiens on 8 August 1918 and lasting until the Armistice of 11 November, it saw the Allied armies break the German defences, including the formidable Hindenburg Line, and drive the enemy back across northern France and into Belgium. The campaign forced Germany’s military leaders to admit that the war was lost.

Background: the tide turns

In the spring of 1918 Germany had launched its great Spring Offensive, gaining large areas of ground but losing hundreds of thousands of its best soldiers. When the Allies counter-attacked on the Marne on 18 July, the initiative passed to them.

The Allied supreme commander, Marshal Ferdinand Foch, planned a series of attacks along the whole front so that the Germans could not concentrate their reserves. By now the Allied armies had learned to combine infantry, artillery, tanks, aircraft and machine guns in what historians call an “all-arms” battle, while more than a million American soldiers had arrived in France.

The British army, rebuilt after its heavy losses in the spring, now included many young conscripts, but its commanders and staff had become far more experienced. The French army, which had recovered from the mutinies of 1917, still held the longest stretch of the front.

Amiens: “the black day of the German army”

The offensive opened at 4:20 am on 8 August 1918 east of Amiens. The British Fourth Army under General Sir Henry Rawlinson, with the Australian Corps under Lieutenant General Sir John Monash and the Canadian Corps under Lieutenant General Sir Arthur Currie, attacked alongside the French First Army. More than 500 tanks supported the attack, and careful secrecy meant the Germans were taken by surprise.

On the first day the Allies advanced about 11 kilometres and captured many thousands of prisoners. Erich Ludendorff later called 8 August “the black day of the German army”, not because of the ground lost, but because so many of his men had surrendered or refused to fight. The Battle of Amiens convinced him and the Kaiser that Germany could no longer win.

Pushing to the Hindenburg Line

Instead of continuing the attack when resistance stiffened, Foch and Haig switched to new sectors. In late August the British Third and Fourth Armies attacked at Albert and Bapaume, and the Australians captured Mont St Quentin and Peronne at the start of September in a celebrated action. On 2 September the Canadians broke the Drocourt-Queant Line near Arras.

On 12 September the newly formed American First Army, under General John J. Pershing, attacked the St Mihiel salient south of Verdun with French support and eliminated it in a few days. By mid-September the German army had been driven back to the Hindenburg Line, a deep system of trenches, concrete strongpoints and barbed wire built in 1916-17.

The Grand Offensive and the Hindenburg Line

Foch launched a coordinated Grand Offensive at the end of September. The French and Americans attacked in the Meuse-Argonne Offensive on 26 September; the British and Canadians crossed the Canal du Nord on 27 September; and a Belgian, British and French group attacked in Flanders on 28 September.

The most important blow fell on 29 September at the St Quentin Canal. The British 46th (North Midland) Division crossed the canal at Riqueval and Bellenglise, some men using lifebelts taken from cross-Channel ferries, while Australian and American troops attacked the tunnel section near Bellicourt. By 5 October the Allies had broken through the last German reserve positions.

Collapse and pursuit

The same week, Bulgaria signed an armistice on 29 September, and Ludendorff told the German leadership that an armistice was needed immediately. Germany’s new government asked President Woodrow Wilson for peace in early October. Ludendorff was dismissed on 26 October.

The fighting continued throughout October and early November. Cambrai fell on 9 October, and battles on the Selle and the Sambre pushed the Germans further back. The German army did not simply collapse in rout. It fought skilful rearguard actions, especially with machine-gun teams, and Allied losses remained heavy to the end. But by early November it was retreating along the whole front, short of men, horses and supplies.

The poet Wilfred Owen was killed in the crossing of the Sambre-Oise Canal on 4 November. On the final morning of the war, Canadian troops entered Mons, where the British army had first fought in August 1914. The fighting ended with the Armistice of 11 November 1918.

Why the Allies won

Historians point to several factors. The Allied armies of 1918 were far more skilled than those of 1916. Artillery could now hit targets accurately without firing ranging shots in advance, thanks to sound-ranging, flash-spotting and better maps, which made surprise possible again. Tanks, aircraft and infantry armed with light machine guns and rifle grenades were combined in carefully planned attacks with limited objectives.

Material superiority also mattered. The Allies had more guns, shells, tanks, aircraft and lorries than the Germans, and the American army added fresh manpower while German reserves dwindled. The blockade had left German soldiers and civilians short of food, and the influenza pandemic weakened both sides, but especially the underfed German army.

German morale was also cracking. After the failure of the spring offensives many soldiers no longer believed victory was possible, and large numbers surrendered rather than fight on. Foch’s strategy of striking repeatedly at different points gave the enemy no time to recover.

The Dominion forces played an outsized part. The Canadian Corps and the Australian Corps, each kept together under its own commanders, were among the most effective formations on the Western Front, and they led many of the key attacks from Amiens to the Hindenburg Line.

Key people

• Ferdinand Foch, the French marshal who coordinated the Allied armies and set the strategy of continuous attacks.
• Douglas Haig, commander of the British Expeditionary Force, whose armies took the largest share of prisoners and guns.
• John Monash and Arthur Currie, commanders of the Australian and Canadian Corps, which spearheaded many of the attacks.
• John J. Pershing, commander of the American Expeditionary Forces.
• Erich Ludendorff, who directed the German war effort and lost his nerve after the defeats of August and September.

By the numbers

Figures differ between sources and national official histories.

Timeline

• 1918, 8 August: The Battle of Amiens opens the offensive.
• 1918, 21 August: British attacks begin at Albert and Bapaume.
• 1918, 31 August - 3 September: Australians take Mont St Quentin and Peronne.
• 1918, 12 September: The Americans attack the St Mihiel salient.
• 1918, 26-28 September: The Grand Offensive begins in the Meuse-Argonne, at the Canal du Nord and in Flanders.
• 1918, 29 September: Battle of the St Quentin Canal; Bulgaria signs an armistice.
• 1918, 9 October: Allied troops take Cambrai.
• 1918, 4 November: Battle of the Sambre.
• 1918, 11 November: The Armistice ends the fighting.

Why it matters

The Hundred Days Offensive was the largest Allied victory of the war and showed how far armies had learned to fight since 1914. It defeated the German army in the field, which undermined later claims that Germany had been “stabbed in the back” at home, and it brought the First World War to an end.