The algorithm of least astonishment

[Vladimir]

Dopp is (as always, it seems :) ) right in saying the apparently weak invasions are actually raids, disruption fodder sent because said faction is too weak to do anything else, but not wanting to bend over either. As katank points out, it's counterproductive through naval invasions most of the time, since ships are costly, but on land it works just fine. If it irritates you, the player, and cuts off one city for even one turn (or cuts trade between cities and forces you to sally to crush them) then mission accomplished .

I can't see any reason why someone would send a unit of pavaise crossbowmen on a raid. That's the absolute worst unit to send on a raid; especially since in that example the raider was Spain and they have Jinettes! Personally I’m all about the raid, I love sending a 5 unit raiding party of mounted X-bows (in M:TW) against someone if I’m just trying to soften them up. I just don’t understand why the (incredibly) AI would send a slow ranged unit on a raid. Raids require speed!