Sticking with WWII, here's the only instance I'm aware of where Caniff drew Hitler. This is one of many posters of the era warning folks to shut up because you never know who might be listening. This poster is ultra rare, but I think the National Archives has one.
Milton Caniff answered many letters and requests for drawings with prints as he hadn't enough time to do individual drawings. What he did do frequently is hand-color the prints. This is the earliest example I've seen of this practice, from around 1936.