the Luce river which ran through the centre of the Canadian's portion of the battlefield. The tanks were successful in this battle, as they attacked German rear positions, creating panic and confusion. The swift advance led to a rapidly spreading collapse in German morale that ultimately led Erich Ludendorff to dub it "the Black Day of the German Army" when he was told of the psychological impact on his men. Continuing to press the advantage gained on Day One, the advance continued for three more days but without the spectacular results of August 8, since the rapid advance outran the supporting artillery that could not be repositioned as quickly as the infantry advanced. By the 10th of August, the Germans had been forced to pull out of the salient that they had managed to occupy during Operation Michael in March, back towards the Hindenburg Line. Left without an enemy to fight or a plan to pursue the retreat the Allied advances in the Amiens sector including those of the Canadians petered out by 13 August and the Amiens operation was halted. The Canadians remained on the scene at Amiens until 22 August, consolidating their gains and prepared to defend against counter-attack. On the 23rd they were summoned to pull out and go into the line east of Arras for an attack that was to commence three days later. There they were stationed in the villages of Fouquescourt, Maucourt, Chilly and Hallu from which they would attack eastward toward the Hindenburg Line. At Amiens the four Canadian Divisions faced and defeated or put to flight ten full German Divisions and elements of five others that sat astride their boundaries with the Australians and French on either side of them. In the five earnest days of fighting between the 8th and 13 August the Canadian Corps captured 9,131 prisoners, 190 artillery pieces, and over 1,000 machine guns and trench mortars. The deepest extent of penetration from their jumping off points was approximately , and in total the Canadians liberated an area of more than which contained 27 towns and villages. Breaking the Hindenburg Line In Arras, the Canadians attacked eastward, smashing the outer defence lines near the powerful Drocourt-Quéant Line (the Wotan Stellung section of the Hindenburg line), along the Arras-Cambrai road. On September 2, 1918, the Canadian Corps smashed the Drocourt-Quéant line, and broke its main support position, taking 5,622 casualties,