Preparation and training for Operation Delta in May and June 1918 provided the Canadian Corps with vital experience for the types of operations conducted during the Hundred Days. Delta was a proposed attack on the southern portion of the Lys salient formed by the German April offensive in Flanders. The operation represented a clear break with the operational concepts employed in 1917 prior to Cambrai. It was a difference between seeing a play diagrammed on a blackboard and actually running it in conditions just short of combat. Having a concrete plan to prepare schemes against was an invaluable element in readying the corps for the strains of the Hundred Days. It helped in overcoming the challenges of ridding the corps of old thinking, mastering the new, and at an accelerated tempo. It was also a valuable rehearsal for the circumstances faced by the corps at Amiens. Finally, it demonstrated how the Canadian Corps differed from the British Army in creating and inculcating a corps level doctrine and the mechanisms used by the senior commanders and staff to disseminate, enforce, and practice it.