<P> There were also to be 580 tanks . The Canadian and Australian Corps were each allocated a brigade of four battalions, with 108 Mark V fighting tanks, 36 Mark V "Star", and 24 unarmed tanks intended to carry supplies and ammunition forward . A single battalion of Mark V tanks was allocated to III Corps . The Cavalry Corps were allocated two battalions each of 48 Medium Mark A Whippet tanks . </P> <P> The Allies had successfully moved the Canadian Corps of four infantry divisions to Amiens without them being detected by the Germans . This was a noteworthy achievement and reflected well on the increasingly efficient staffwork of the British armies . A detachment from the Corps of two infantry battalions, a wireless unit and a casualty clearing station had been sent to the front near Ypres to bluff the Germans that the entire Corps was moving north to Flanders . The Canadian Corps was not fully in position until 7 August . To maintain secrecy, the Allied commanders pasted the notice "Keep Your Mouth Shut" into orders issued to the men, and referred to the action as a "raid" rather than an "offensive". </P> <P> Although the Germans were still on the offensive in late July 1918, the Allied armies were growing in strength, as more American units arrived in France, and British reinforcements were transferred from the Home Army in Britain and the Sinai and Palestine Campaign . The German commanders realised in early August that their forces might be forced onto the defensive, though Amiens was not considered to be a likely front . The Germans believed the French would probably attack the Saint - Mihiel front east of Rheims, or in Flanders near Mount Kemmel, while they believed the British would attack along either the Lys or near Albert . The Allies had indeed mounted a number of local counter-offensives in these sectors, both to gain local objectives to improve their defensive positions and to distract attention from the Amiens sector . German forces began to withdraw from the Lys and other fronts in response to these theories . The Allies maintained equal artillery and air fire along their various fronts, moving troops only at night, and feigning movements during the day to mask their actual intent . </P> <P> The German front east of Amiens was held by their Second Army under General Georg von der Marwitz, with six divisions in line (and two facing the French 1st Army). There were only two divisions in immediate reserve . There was some concern among the Allies on 6 August when the German 27th Division actually attacked north of the Somme on part of the front on which the Allies planned to attack two days later . The German division (a specially selected and trained Stosstruppen formation) penetrated roughly 800 yards (730 m) into the one - and - a-half mile front . This attack was made in retaliation for a trench raid by the 5th Australian Division north of the Somme on the night of 31 July, which had gained many prisoners, before the Australian Corps was concentrated south of the river . The German division moved somewhat back to its original position on the morning of 7 August, but the movement still required changes to the Allied plan . </P>

When did the battle of amiens take place