Although I mentioned the Veterans Guard before, the article linked yesterday has a description that's worth a post by itself. (paragraph breaks added)

As early as May 1940, the Department had created a new organization called the Veteran Guards of Canada. They assumed responsibility for guarding the captured soldiers in May 1941. The Veteran Guards consisted mostly of First World War veterans too old for battlefront duty. The maximum age for duty was fifty, but many slipped in despite their age.

Veteran Guard units were formed across Canada and they were assigned several different tasks ranging from guarding military targets, dams, bridges, power plants to government installations. The most important assignment, however, was guarding POW’s. From an initial limited recruitment of a few hundred men, the Veteran Guards of Canada expanded to over 10,000 by 1943 and was 15,000 strong by 1945.

At first glance, the aging First World War veteran seemed an unlikely candidate for guarding extremely well trained battle hardened enemy soldiers. Yet the guards possessed experience, and many had been POW’s themselves in WWI. They understood the prisoner mentality and the regimen of a controlled life. The Veteran Guards were used extensively in all parts of Canada including the bush camps located on Lake of the Woods.

(The image is from a history page that mentions the Veterans Guards, and isn't related to the Lake of the Woods article.)