HISTORY! 50 POINTS PLEASE do not answer this as an opinion, I need to do my assignment.

Question: During the second world war, which nation had the strongest and most
effective army?

Please give your answer along with three reasons and
explanations. Make sure to write your answer in 2-3 paragraphs. Each
paragraph must be anywhere from 4-5 sentences.

My answer is that the Soviet Union was the strongest, but I only have one reason.
Can someone help me find two more? I tried googling answers, but it isn't giving me anything besides the info i already used.

(Also, I looked it up, and it does say that the Soviet Union was the most powerful. That's not my opinion.)