On March 21, 1918, the Germans launched a violent attack against the Fifth and Third British Armies. The battle resulting from this attack, known as the Battle of Amiens, did not involve directly the majority of the Canadian Corps. The latter on that date was disposed as follows: Third Canadian Division (Major General L. J. Lipsett), in the line, Mericourt-Avion sections; Fourth Canadian Division (Major General Sir D. Watson), in the line, Lens-St.-Emile sections; First Canadian Division (Major General Sir A. C. Macdonell), in the line, Hill 70 section; Second Canadian Division (Major General Sir H. E. Burstall), resting, Auchel area. In the afternoon orders were received to take over the front of the Sixty-second Division (Thirteenth Corps) in the Acheville sector. The Second Canadian Division, then in reserve, was at first chosen to execute this order. But when, somewhat later, the Canadian Corps was instructed to keep one complete division in reserve, this order was canceled, and instead the Third Canadian Division was ordered to execute its frontage by relieving the Sixty-second Division in the Acheville-Arleux sector, making the total Canadian front 17,000 yards. In the evening of March 22, 1918, the Hill 70 sector, then held by the First Canadian Division, was taken over by the Fourth, extending the latter's frontage, while the former was placed in reserve. Late that night General Headquarters ordered the withdrawal of the First Canadian Motor Machine-Gun Brigade (Lieutenant Colonel W. K. Walker) from the Vimy sector. This unit, the next morning, moved south to the support of the Fifth Army, and by midnight of March 23, 1918, having traveled over 100 miles during the day, all batteries were in action on a thirty-five-mile front east of Amiens. Under orders of the Fifth and later of the Fourth Army, it was ordered to fight a rear-guard action to delay the advance of the enemy and to fill dangerous gaps on the army fronts. For nineteen days this unit was continuously in action north and south of the Somme, fighting against overwhelming odds. Using to the utmost its great mobility, it fought over 200 square miles of territory. It is difficult to appraise in its correct extent the influence--material and moral--that the forty machine guns of this unit had in the events which were then taking place. The losses suffered amounted to about 75 per cent of the trench strength of the unit, and to keep it in being throughout that fighting, reenforcements by personnel of the infantry branch of the Canadian Machine-Gun Corps were authorized. On the 23d, at 10.50 a. m., the Second Canadian Division was ordered to concentrate at once west of Arras in the Mont St.-Eloi area, and having carried this out, passed into General Headquarters reserve.