Germany got punished hard for losing the previous war. A global recession made the punishment even harder. A corporal who had failed as an artist after the war found he had a gift for riling up the masses. He clawed his way to the top of a party, then the country. Then he started empire building to make up for the raw deal and the recession. It gave people there something to do. The Japanese had similar ideas. They were empire building. They both decided to not fight though, because fighting from that far away is hard. Oh, BTW, the German guy hated odd people; but especially Jews and tried to kill them all. Some smart ones left mostly for Britain and the USA. This will be important later. So the German empire at its height was trying to conquer Britain and the USSR and had plainly bitten off more than it could chew. The Japanese empire also got to the point where it expanded and pissed off the USA, which had sort of wanted to help Britain because they're the mother country but couldn't find a good excuse. So now that we had an excuse the USA sent its military and a TON of equipment. Along with Britain and the USSR they got Germany under control. Japan was a bit harder; but remember those Jews I mentioned? They built one helluva bomb. The end.