there is a much bigger photomanipulation community here and they cannot get divorced from 'Digital Art' no matter how nicely they ask so I have doubts anout them allowing another forum, but you can always ask I suppose.
"Why was Gallipoli a total failure for the Allies?" "Napoleon V. Robert E. Lee: Who would win?" "The Pacific Battle fleet finds out about the Japanese's plan & leaves Pearl Harbor to confront the Japanese aircraft carriers a few miles away: What happens?" "If Rommel were to fight in The War on Terror, how would he do?"
Interesting topics, and I don't think they'd be unwelcome on this forum as such. I'd say I would be fairly clueless on answering any of them, except to say that Rommel would be an awful commander to counter a terrorist/guerrilla threat - Goebbels would probably have been much more successful.