The Hundred Days Offensive (8 August to 11 November 1918) was a series of massive Allied offensives that ended the First World War. Beginning with the Battle of Amiens (8–12 August) on the Western Front, the Allies pushed the Imperial German Army back, undoing its gains from the German spring offensive (21 March – 18 July).

The Germans retreated to the Hindenburg Line, but the Allies broke through the line with a series of victories, starting with the Battle of St Quentin Canal on 29 September. The offensive led directly to the Armistice of 11 November 1918 which ended the war with an Allied victory. The term "Hundred Days Offensive" does not refer to a planned Allied campaign, but rather the rapid series of Allied victories.

Background

The German spring offensive on the Western Front had begun on 21 March 1918 with Operation Michael and had petered out by July. The German Army had advanced to the River Marne, but failed to achieve their aim of a victory that would decide the war. When the German Operation Marne-Rheims ended in July, the Allied supreme commander, Ferdinand Foch, ordered a counter-offensive, which became known as the Second Battle of the Marne. The Germans, recognizing their untenable position, withdrew from the Marne to the north. For this victory, Foch was granted the title Marshal of France.

After the Germans had lost their forward momentum, Foch considered the time had arrived for the Allies to return to the offensive. General Pershing who commanded the American Expeditionary Force (AEF) was keen to use his army as an independent force. The British Expeditionary Force (BEF) had been reinforced by large numbers of troops returned from the Sinai and Palestine campaign and from the Italian front, and by replacements previously held back in Britain by Prime Minister David Lloyd George.

The military planners considered a number of proposals. Foch agreed to a proposal by Field Marshal Sir Douglas Haig, commander-in-chief of the BEF, to strike on the River Somme, east of Amiens and south-west of the site of the 1916 Battle of the Somme, to force the Germans away from the vital Amiens–Paris railway. Through careful preparation, the Allies achieved surprise. The attack, led by the British Fourth Army, broke through the German lines, and tanks attacked German rear positions, sowing panic and confusion. By the end of the day, a gap wide had been created in the German line south of the Somme. The Allies had taken 17,000 prisoners and 339 guns. Total German losses were estimated to be 30,000 men, while the Allies had suffered about 6,500 killed, wounded and missing. The collapse in German morale led Erich Ludendorff to dub it "the Black Day of the German Army".

The advance continued for three more days but without the spectacular results of 8 August, since the rapid advance outran the supporting artillery and ran short of supplies. During those three days, the Allies had managed to gain . Most of this was taken on the first day as the arrival of German reinforcements after this slowed the Allied advance. On 10 August, the Germans began to pull out of the salient that they had managed to occupy during Operation Michael in March, back towards the Hindenburg Line.

Somme

thumb|1 September 1918, [[Péronne, Somme. A machine gun position established by the Australian 54th Battalion during its attack on German forces in the town]]

Haig refused to continue the attack and instead prepared to launch a fresh offensive by the Third Army at Albert (the Battle of Albert), which opened on 21 August. The attack was widened on the south, by the French Tenth Army starting the Second Battle of Noyon on 17 August, capturing the town of Noyon on 29 August. On 26 August, to the north of the Somme, the First Army widened the attack by another with the Second Battle of Arras of 1918, which includes the Battle of the Scarpe (1918) (26 August) and the Battle of Drocourt-Queant Line (2 September).

South of the BEF, the French First Army approached the Hindenburg Line on the outskirts of St. Quentin during the Battle of Savy-Dallon (10 September), and the French Tenth Army approached the Hindenburg Line near Laon during the Battle of Vauxaillon (14 September). Before Foch's main offensive was launched, the remaining German salients west and east of the line were crushed at Havrincourt and St Mihiel on 12 September and at the Battle of Épehy and the Battle of the Canal du Nord on 27 September.

On 29 September, the central attack on the Hindenburg Line commenced, with the British Fourth Army (with British, Australian and American forces) attacking in the Battle of St Quentin Canal and the French First Army attacking fortifications outside St Quentin. By 5 October, the Allies had broken through the entire depth of the Hindenburg defences over a front. This collapse forced the German High Command to accept that the war had to be ended. The evidence of failing German morale also convinced many Allied commanders and political leaders that the war could be ended in 1918; previously, all efforts had been concentrated on building up forces to mount a decisive attack in 1919.

Subsequent operations

thumb|Comparison of Allied and German frontline rifle strength before and after the Hundred Days Offensive and the arrival of additional American troops.

Through October, the German armies retreated through the territory gained in 1914. The Allies pressed the Germans back toward the lateral railway line from Metz to Bruges, which had supplied the front in northern France and Belgium for much of the war. As the Allied armies reached this line, the Germans were forced to abandon increasingly large amounts of heavy equipment and supplies, further reducing their morale and capacity to resist.

The Allied and German armies suffered many casualties. Rearguard actions were fought during the Pursuit to the Selle (9 October), battles of Courtrai (14 October), Mont-d'Origny (15 October), the Selle (17 October), Lys and Escaut (20 October) (including the subsidiary battles of the Lys and of the Escaut), the Serre (20 October), Valenciennes (1 November), the Sambre (including the Second Battle of Guise) (4 November), and Thiérache (4 November), and the Passage of the Grande Honnelle (5 November), with fighting continuing until the Armistice took effect at 11:00 on 11 November 1918. The last soldier to die was Henry Gunther, one minute before the armistice came into effect.

See also

  • Canada's Hundred Days

Notes

References

Bibliography

  • Lloyd, Nicholas: Hundred Days Offensive, in: 1914–1918 – online. International Encyclopedia of the First World War.
  • Maps of Europe during the Allied Hundred Days Offensive at omniatlas.com