"Curse them, an ambush"
No worries I think. I allocate a task to pull the lever to raise my drawbridge. Sadly I have a lot of dwarves outside my magma moat, looting the caravan the previous goblin ambush had done away with. The goblins aren't near the bridge, I have time for a daring rescue. I activate the military and it turns out all of them are already outside, looting. It kicks off.
"Curse them, an ambush"
No worries. This time, a mere two squares from my gatehouse, but that thing has five layers of cage and weapon trap.
"Curse them, an ambush"
I worry. The combined might of 15 goblins overwhelms my 20 strong militia in the open. The goblins that swarmed the gatehouse are all dead or caged though.
"Curse them, an ambush"
...ok. The remainder of the horde surges over my traps and loses a lot of their number, but they breach the gap and kill the dwarf running for the drawbridge lever.
"Curse them, an ambush"
STOP IT
"Curse them, an ambush"
I go fetal
"Curse them, an ambush"
37 goblins in total, swarming the fortress. The last 17 of my dwarves withdraw to the crypts, the lowest level of my fortress. Each of those still standing assigned a tomb, I pray that somebody is left to lay them in it. The battle of Claspbronze is met. The last dwarf standing flees to a corner to die bleeding and alone, huddled against his own coffin.
"Curse them, an ambush"
I have had fun.
Next time I have a moat, I'm either going to make it big enough to warrant my dwarves never leaving it and only lower the drawbridge for special occasions, or I'm making a seperate lever house in which there will be a jobless dwarf, walled in with a food supply who will exist only to instantly pull the siege levers.