I had an awesome discussion set up for today's UU, but I accidentally closed the window. I'll still post, but I was really happy with how that one shaped up.
Anyway, with only a week left to go (time to start counting hours!), we'll look at an underdiscussed unit: the Roman
Ballista. Essentially a gigantic crossbow, its Civ5 representative reflects its devastating capabilities:
+4 ranged combat strength (18) over generic Catapults.
I've been unfair to siege thus far in the thread, as they didn't strike me as particularly useful in maneuver-heavy Civ5 combat. Why bother setting up to fire, when battles move so quickly? I realized, however, that siege is more useful than it first appears in field combat due to its devastating strength. The Ballista, with its 18 ranged strength, is as powerful as a Knight at range - when applied in the Iron Age, when most units have ~10 strength, it can seriously weaken an enemy's troops. So long as you can draw them into firing range (via crafty maneuvering of other units), the Roman player can dominate a battlefield with his siege engines. To say nothing of where the Ballista truly shines, city conquest: point these at a city, let fire, and your Legion/Horsemen's jobs just became easy. With 18 strength, it's unlikely any city will stand for very long against your assault.
Just be wary of the fact that they still have the Catapult's base strength of 4, making them on par with Archers in melee. If Horsemen get back to your Ballista, things will go poorly for Rome; given that the lowly
Scout has 4 strength, you should keep careful guard of your siege engines.