WWII wasn't even really one war. It was two wars fought at the same time. The link between Germany and Japan is almost completely insignificant. Each war had different causes, and as has been mentioned, all of history is simply the result of something else. To say that they were the SAME war fought for the SAME reasons is incorrect, but it's quite correct to say that what caused WWII was developed a good deal in WWI. Ask yourself this... would WWII have happened if WWI hadn't?