These are the top 5 strongest armies in WW2... 1.Germany They were rising to power and had a powerful army. They were recovering from WW1. They were to become the first country to study nuclear weaponry. However, the plans were stolen by Russia and the US. 2.Japan With help from Germany, they rose to power a well. However, instead of rising to power in Europe, they rose to power in Asia and the Pacific. Taking over countries such as China and the Phillippines. 3.Russia Russia was a rising power from the Allies. They waged a war against Germany for attacking them. Stalin rule Russia with an " iron fist ". 4.USA The US as well was a rising force. They were getting more European immigrants ( From Russia, Poland, France etc. ). 5.UK ( Or Britain ) Britain continued to wage war against Germany