was shell-torn and often impassable to traffic. Following Operation Michael, Germany launched Operation Georgette against the northern English Channel ports. The Allies halted the drive after limited territorial gains by Germany. The German Army to the south then conducted Operations Blücher and Yorck, pushing broadly towards Paris. Germany launched Operation Marne (Second Battle of the Marne) on 15 July, in an attempt to encircle Reims. The resulting counter-attack, which started the Hundred Days Offensive, marked the first successful Allied offensive of the war. By 20 July, the Germans had retreated across the Marne to their starting lines, having achieved little, and the German Army never regained the initiative. German casualties between March and April 1918 were 270,000, including many highly trained stormtroopers. Meanwhile, Germany was falling apart at home. Anti-war marches became frequent and morale in the army fell. Industrial output was half the 1913 levels. Hundred Days Offensive The Allied counteroffensive, known as the Hundred Days Offensive, began on 8August 1918, with the Battle of Amiens. The battle involved over 400 tanks and 120,000 British, Dominion, and French troops, and by the end of its first day a gap long had been created in the German lines. The defenders displayed a marked collapse in morale, causing Ludendorff to refer to this day as the "Black Day of the German army". After an advance as far as , German resistance stiffened, and the battle was concluded on 12 August. Rather than continuing the Amiens battle past the point of initial success, as had been done so many times in the past, the Allies shifted attention elsewhere. Allied leaders had now realised that to continue an attack after resistance had hardened was a waste of lives, and it was better to turn a line than to try to roll over it. They began to undertake attacks in quick order to take advantage of successful advances on the flanks, then broke them off when each attack lost its initial impetus. The day after the Offensive began, Ludendorff said: "We cannot win the war any more, but we must not lose it either." On 11 August, he offered his resignation to the Kaiser, who refused it, replying, "I see that we must strike a balance. We have nearly reached the limit of our powers of resistance. The war must be ended." On 13 August, at Spa, Hindenburg, Ludendorff, the Chancellor, and Foreign Minister