The Armed Services Editions program was an American effort to provide reading material to WW II Armed forces. With 123 million books distributed I imagine many of 1322 titles ended up in Canadian hands. There wasn't a similar program in Canada but publishers did encourage Canadians to send books in the "Service" parcel. An example from the White Circle imprint published by Wm. Collins Sons & Co. Canada is below.
The ASE program continued to September 1947. The last year's books were published in the usual mass market format rather than the vertical format.
White Circle 63 - 1943
White Circle 63 back
ASE T-2 back
ASE 1244 back