Much has been written on the Canadian Corps and the string of victories that it achieved after its initial triumph at Vimy Ridge. The corps did not have a perfect record after Vimy, although the battles are often depicted as such. The attack on the town of Lens in August 1917 demonstrated that the corps was still capable of making mistakes that were extremely costly in casualties and did not garner any sort of victory.
Examining the battle of Lens will dispel some of the myths. The brief literature on Hill 70 and Lens has always lumped them together as a single battle with a victorious outcome. In fact, this is misleading. The attack on Lens, which immediately followed the highly successful assault on Hill 70, was a defeat, and an avoidable one. Hill 70 was an operation involving 14 assaulting battalions launched on a much wider front than the seven attacking battalions that led the assault into Lens. Lens was not a probing assault that followed the success of Hill 70—it was a set–piece battle that the Canadian Corps Headquarters planned in July. This paper will show why the same sort of set–piece battle plan the Canadians applied with such success at Vimy Ridge and Hill 70 failed at Lens.
Jackson, Geoff "“Anything but Lovely”: The Canadian Corps at Lens in the Summer of 1917." Canadian Military History 17, 1 (2008)