The Battle of Amiens, also known as the Third Battle of Picardy (), was the opening phase of the Allied offensive which began on 8 August 1918, later known as the Hundred Days Offensive, that ultimately led to the end of the First World War. Allied forces advanced over on the first day, one of the greatest advances of the war, with Gen Henry Rawlinson's British Fourth Army (with 9 of its 19 divisions supplied by the fast moving Australian Corps of Lt Gen John Monash and Canadian Corps of Lt Gen Arthur Currie) playing the decisive role. The battle is also notable for its effects on both sides' morale and the large number of surrendering German forces. This led Erich Ludendorff to later describe the first day of the battle as "the black day of the German Army". Amiens was one of the first major battles involving armoured warfare. Prelude On 21 March 1918, the German Army had launched Operation Michael, the first in a series of attacks planned to drive the Allies back along the length of the Western Front. After the signing of the Treaty of Brest-Litovsk with revolutionary-controlled Russia, the Germans were able to transfer hundreds of thousands of men to the Western Front, giving them a significant, if temporary, advantage in manpower and material. These offensives were intended to translate this advantage into victory. Operation Michael was intended to defeat the right wing of the British Expeditionary Force (BEF), but a lack of success around Arras ensured the ultimate failure of the offensive. A final effort was aimed at the town of Amiens, a vital railway junction, but the advance had been halted at Villers-Bretonneux by British and Australian troops on 4 April. Subsequent German offensivesOperation Georgette (9–11 April), Operation Blücher-Yorck (27 May), Operation Gneisenau (9 June) and Operation Marne-Rheims (15–17 July)all made advances elsewhere on the Western Front, but failed to achieve a decisive breakthrough. By the end of the Marne-Rheims offensive, the German manpower advantage had been spent and their supplies and troops were exhausted. The Allied general, General Ferdinand Foch, ordered a counteroffensive which led to victory at the Second Battle of the Marne, following which he was promoted to Marshal of France. The Germans, recognising their untenable position, withdrew from the Marne to the north. Foch now tried to move the Allies back onto the offensive. Plan Foch disclosed his plan