The National Interest listed six armies from different times in human history, which in the magazine's opinion had the ability to "win battles decisively and consistently and the extent to which they allowed their countries to dominate other states."
It's hard to judge which army was more powerful, especially considering most of them never had to fight each other directly, with the exception of the armies of Nazi Germany and the Soviet Union.
It's amusing to see the army of Nazi Germany put higher on the list than the Soviet Union's Red Army, especially since the Soviets defeated the Nazis during World War II.
Overall, the National Interest's piece is an interesting read, but trying to make the list of the world's most powerful armies from different times in history is akin to having never-ending arguments about which animal is stronger — a lion or a grizzly bear — or which martial artist is stronger pound-for-pound — great heavyweight Fedor Emelianenko or undefeated women's bantamweight champion Ronda Rousey.