Ron Bernstein writes…
You're quite right that that Wikipedia line about Mort Walker's WWII years is screwy. Like you said, Colonel Klink commanded a German P.O.W. camp. What Mort Walker commanded was an American P.O.W. camp that housed German prisoners of war. Here's a link to an article in which he tells about it.
Thanks, Ron. That makes a lot more sense. The linked article is behind the Washington Post pay-after-reading-X-number-of-articles-each-month-wall so here's the relevant quote: "Once he landed in Europe, the forces didn't know what to do with Walker — so he was put in command of a prisoner-of-war camp. "So I had 10,000 Germans in a P.O.W. camp in Naples," he says. "They made me an intelligence officer. I investigated thefts and rapes and murders — all kinds of stuff." That makes a lot more sense.