Silvertemple is practically impregnable. A winding staircase carved into the vertical cliff at a great waterfall with fortifications on the other side of the brook to allow marksdwarves to pepper invaders and cause them to fall 7-10 z-levels to their gory deaths on the rocks below. When a goblin ambush appeared, killing a woodcutter, I had no worries about sending the militia of 18 competent dwarves to the surface to deal with it. In the unlikely event of failure I would simply wait for them by the waterfall and take them out as they tried to get to the entrance hall. In the middle of the ensuing fight (which saw several goblins toppling over the edge of the cliff to explode against the rocks below) the walking dead appear. Not ten. Not twenty. More than a hundred of them. I had about the same number of dwarves, but the vast majority of those were in no state to fight the undead horde. I desperately pull everyone inside, abandoning two recruits and a gnarled militia commander to distract them as some fisherdwarves got to safety.
For a year the zombies have been sitting at the surface. Waiting.
For a year Silvertemple has slaved over the magmaforges, churning out maces, hammers and armour to equip the remaining population for the liberation.
But recently the goblins have come back in numbers. Ambush after ambush is being sprung at the surface; brave goblin archers giving up their lives to take out the undead. And they are winning. Little by little, their numbers are dwindling. Only about 30 of the abominations remain and I now stand a chance.
Everything I thought I knew is being overturned. I'm not sure I can go back to goblinslaying as a passtime now...