"Pardon My Helmet" from Our Army at War #157 (DC, 1965) by Robert Kanigher and Joe Kubert
Our Army at War lasted a whopping 301 issues (from 1952 to 1977), but of course, it had the best war strips: Sgt. Rock and Easy Company from #81, and Enemy Ace from #151. It didn't really end with #301 though, it was simply retitled Sgt. Rock and lasted another 11 years! I don't think there's another war comic that lasted 422 issues.