They couldn't "defend", undead wouldn't attack the city, just wait for cows to starve. Still, it's a point that going to fight in formation would seem much less sucicidam then trying to drown the undead and go berserk on them jumping out from the tide... We'll see how our Game Master see the odds. I would be pretty satisfied with plot on Tauren getting wiped out and the last living one going on crusade against undead and orcs in alliance with elfs and with whatever/whoever he tried to "reforge" it with... :]
Arvold
I don't think that was smart at all. They didn't consider undeads racial skill. Defending would be much more efficient. They would fight on cliff.