Here they are in no particular order.

1. Napoleon’s Grand Armee

Out of the fires of the revolution, Napoleon assembled an incredibly professional force, filled with a strong espirit de corps, that took on practically all the nations of Europe. If not for a few pesky countries around the borders they might have conquered the whole thing.

2. Gengis Khan’s Mongol Horde

Riding small horses and wearing little armour, these warriors came pouring out of the steppes in every direction.  They scoffed at the Great Wall of China before taking over vast tracks of Asia. They also pushed into Europe winning countless battles. If not for the death of the Khan, who knows how far they could have reached?

3. Alexander the Great’s Army

Sure the army was basically a present from his dad, but Alexander took it and marched all over the known world. Really his conquests only stopped when his army realized just how long it was going to take them to march home… 

4. Nazi Germany

Suffering under the Treaty of Versailles, the Germans proved they still had a lot of fight left in them when they blitzkrieged all over Europe, knocking down countries like toy soldiers. If not for a few pesky countries around the borders of Europe, and a bit of overseas intervention, they might have conquered the whole thing.

5. The Roman Legions

No state survives for a thousand years without a pretty good military force, and the Roman Legions were the best of their time. Sure, they lost some battles, even suffered a few really bad defeats, but considering they marched all over the known world, usually fighting battles where they were badly outnumbered, they ended up with a pretty good score.  

Of course, this is all open to discussion…