Oh man, that was so awesome. I had a much larger force than the gauls I was besieging so I decided I'd try to minimize casualties as much as possible.
I send a couple of light infantry merc units in first with a battering ram, with my velites bombing javelins over the walls. The ram gets through and I charge into the city. The mercs get jammed up right at the gate and aren't making any progress against the barbarians, so I let slip the dogs of war, literally. Like 80 dogs go running into the melee and pretty soon the barbarians are running for the town center to make a final stand. The dogs keep chasing them so I send the mercenaries along for the run, and the battle is pretty much over from that point on.
The puppies got the kill on the enemy general too. Looks pretty freaky seeing 50 or 60 dogs climbing all over a formation.