The joke is certainly reminiscent of Burr Shafer’s style (single panel cartoon, a character saying something utterly clueless about an important historical event). Shafer’s career lasted from the 1930s through the 1950s (Harry Truman was a fan, reportedly saying “I’m very proud that I’m smart enough to get the point.”) I have read most of the collections of his J. Wesley Smith cartoons. That said, I don’t recall him making that particular joke.