Operation "Alberich (Unternehmen Alberich") was the codename of a German military operation in France during World War I.
 It was a planned withdrawal to new positions on the shorter, more easily defended Hindenburg Line ("Siegfriedstellung"), which took place between 9 February and 20 March 1917 and eliminated the two salients which had been formed in 1916, between Arras and Saint-Quentin and from Saint-Quentin to Noyon, during the Battle of the Somme.
 The British referred to it as the "German Retreat to the Hindenburg Line" but the operation was a strategic withdrawal rather than a retreat under pressure.
The Hundred Days Offensive was the final period of the First World War, during which the Allies launched a series of offensives against the Central Powers on the Western Front from 8 August to 11 November 1918, beginning with the Battle of Amiens.
 The offensive essentially pushed the Germans out of France, forcing them to retreat beyond the Hindenburg Line, and was followed by an armistice.
 The term "Hundred Days Offensive" does not refer to a specific battle or unified strategy, but rather the rapid series of Allied victories starting with the Battle of Amiens.
The Battle of Verdun ("Bataille de Verdun", ] , "Schlacht um Verdun", ] ), fought from 21 February to 18 December 1916, was the largest and longest battle of the First World War on the Western Front between the German and French armies.
 The battle took place on the hills north of Verdun-sur-Meuse in north-east France.
 The German 5th Army attacked the defences of the Fortified Region of Verdun ("RFV, Région Fortifiée de Verdun") and those of the French Second Army on the right bank of the Meuse.
 Inspired by the experience of the Second Battle of Champagne in 1915, the Germans planned rapidly to capture the Meuse Heights, an excellent defensive position with good observation for the artillery to bombard Verdun.
 The Germans hoped that the French would commit their strategic reserve to recapture the position and suffer catastrophic losses in a battle of annihilation, not costly for the Germans because of their tactical advantage.
Operation "Michael" was a major German military offensive during the First World War that began the Spring Offensive on 21 March 1918.
 It was launched from the Hindenburg Line, in the vicinity of Saint-Quentin, France.
 Its goal was to break through the Allied (Entente) lines and advance in a north-westerly direction to seize the Channel ports, which supplied the British Expeditionary Force (BEF) and to drive the BEF into the sea.
 Two days later General Ludendorff, the Chief of the German General Staff, changed his plan and pushed for an offensive due west, along the whole of the British front north of the River Somme.
 This was designed to separate the French and British Armies and crush the British forces by pushing them into the sea.
 The offensive ended at Villers-Bretonneux, to the east of the Allied communications centre at Amiens, where the Allies managed to halt the German advance; the German Armies had suffered many casualties and were unable to maintain supplies to the advancing troops.
Alvin Cullum York (December 13, 1887 – September 2, 1964), also known as Sergeant York, was one of the most decorated United States Army soldiers of World War I.
 He received the Medal of Honor for leading an attack on a German machine gun nest, taking 35 machine guns, killing at least 25 enemy soldiers, and capturing 132.
 York's Medal of Honor action occurred during the United States-led portion of the Meuse-Argonne Offensive in France, which was intended to breach the Hindenburg line and force the Germans to surrender.
The Battle of St Quentin Canal was a pivotal battle of World War I that began on 29 September 1918 and involved British, Australian and American forces operating as part of British Fourth Army under the overall command of General Sir Henry Rawlinson, 1st Baron Rawlinson.
 Further north part of the British Third Army also supported the attack, whilst to the south of the twelve-mile (19 km) Fourth Army front the First French Army launched a coordinated attack on a six-mile (9.5 km) front.
 The objective was to break through one of the most heavily defended stretches of the German "Siegfriedstellung" (Hindenburg Line), which in this sector utilised the St Quentin Canal as part of its defences.
 The assault achieved its objectives (though not according to the planned timetable), resulting in the first full breach of the Hindenburg Line, in the face of heavy German resistance.
 In concert with other attacks of the Great Offensive along the length of the line, Allied success convinced the German high command that there was little hope of an ultimate German victory.
The Hindenburg Line ("Siegfriedstellung" or Siegfried Position) was a German defensive position of World War I, built during the winter of 1916–1917 on the Western Front, from Arras to Laffaux, near Soissons on the Aisne.
 In 1916, the German offensive at the Battle of Verdun had been a costly failure.
 The Anglo-French offensive at the Battle of the Somme had forced a defensive battle on the Germans, leaving the western armies ("Westheer") exhausted.
 On the Eastern Front, the Brusilov Offensive had inflicted huge losses on the Austro-Hungarian armies in Russia and forced the Germans to take over more of the front.
 The declaration of war by Romania had placed additional strain on the German army and war economy.
 Construction of the Hindenburg Line in France was begun by the Germans in September 1916, to make a retirement from the Somme front possible, to counter an anticipated increase in the power of Anglo-French attacks in 1917.
The Dury Memorial is a World War I Canadian war memorial that commemorates the actions of the Canadian Corps in the Second Battle of Arras, particularly their breakthrough at the Drocourt-Quéant Line switch of the Hindenburg Line just south of the town of Dury.
 The Drocourt-Quéant Line was a main position in the German Army's defensive position in the area.
 The action took place on 2 and 3 September 1918 during a period known as the Hundred Days Offensive or Canada's Hundred Days.
 Particularly noteworthy for such a brief battle was that seven Canadians earned a Victoria Cross on 2 September during the battle.
Major General Edward Mann Lewis, KCMG, (December 10, 1863 – July 27, 1949) was a highly decorated United States Army officer who served his nation for 46 years.
 In World War I he led the 30th Infantry Division when they broke the Hindenburg Line.
 Upon arrival in France In 1917, he was placed in command of all U.S. forces in Paris.
 In 1918 he led the 3rd Brigade of the 2nd Infantry Division at Château-Thierry where he was responsible for planning and leading the attack on the strategic town of Vaux.
 General John J. Pershing then promoted him and placed him in command of the 30th Infantry Division in July 1918.
 Assigned to the Fourth British Army, the 30th Division (Old Hickory) broke the Hindenburg Line on September 29, hastening the end of the Great War.
The Battle of the Scarpe was a World War I battle that took place during the Hundred Days Offensive between 26 and 30 August 1918.

Question: What battle took place during an offensive that pushed the Germans out of France, forcing them to retreat beyond the Hindenburg Line?
Answer: Battle of the Scarpe