Rome vs Japan

[P. Lilius Frugius Simius]

It should also be noted that in the civil wars of the 15th-16th centuries the samurai and their ashigaru (light foot) supporters pretty much dropped the old individualistic glory-hound style of fighting and fought in dense ranks armed with long spears. Romans fighting a Japanese army of this period would be facing something resembling a formation of Swiss pikemen, a very different proposition from the Japanese armies of earlier centuries.

But not very unlike to the Macedonian phalanx they had already beaten in the Republican era... While important, the Japanese spear massed formations needed both arrow and musket support to be effective, specially against cavalry raids from the flank, like all spear formations...

It's an interesting what-if question, but we should consider lots of matters, not just weapon length or armor availability, in a one-on-one stance, the personal value as fighter of each one is also as important. The best fighter would probably win over the other, each one using their own weapons and armor... Again, not the same a Sengoku Jidai veteran than a XVIII Tokugawa officer, martials arts training (kobujutsu ryûha) or not...

signing off, back to work :-P P