It's year 2 of the fortress, and I'm at 48 dwarves. I've got 8 recruits in the military, and steel armor is just starting to come off the production line. So aside from the fact that I can lock myself down, I'm not really prepared for the necromancer siege that shows up.
Still, I'm in pretty good shape. The fort is airtight, I've got all kinds of metal, and my cage traps already picked off two stealth necromancers that are going to be really useful later. So it seems to me that it makes sense to sit there and build enough cage traps to pen the entire siege, about 50 zombies, so I'll have some toys to play with once I get my necro arena up.
So I carve out a long L-shaped tunnel, put drawbridges at both ends, and build a huge load of cages. When it's ready, I station my fledgling military two z-levels down and way at the north end of the map, and dig a ramp to the surface way at the south end. The miner successfully opens the passage up and heads back toward safety, and the legions of the dead start shambling in.
And here comes the goddamn cavalry. One by one, the recruits charge down the corridor, despite their station orders, despite the fact that they have no earthly way of knowing the undead are there. They don't stand a chance.
Turns out I left an armor stand out front of the main entrance and they were allowed to train there. I guess despite the Station order, they just decided they were going to get to that kicking demonstration by any means necessary.