A white tigerman siege came a knocking led by the civ's general, and I'm not sure if they're astoundingly stupid even by DF standards or the ballsiest mother fuckers ever, but they cam in riding boozebelly goats. No matter which it is, I'm counting my blessings as about half way through the siege three of my soldiers decided that the middle of a battle was the perfect time to take a nap and since they couldn't path to their beds, just crashed out in the middle of the battlefield.
Mercifully, the boozebelly mounts are complete cowards, which is probably what saved all their lives, and the only noncowardly mounts in the attack were already dead with their owners and the general, due to a severe case of "crushed head" syndrome. The tigermen however instead died of "Lungs-crushed-with-hammer-or-mace" syndrome. I have also found Tigermen are large enough that helmets make it next to impossible to score a quick kill even with wolfram hammers, so to simply save myself the headache of watching my men waste time on an incapacitated target, I now have to remember to autodump all helmets off of white tigermen. I'd train some swordsmen to deal with such things, but I'm still pants-shittingly terrified of necromancers.