So, I'm in the middle of an Orc siege. I have about 40 dwarves. They had done a lot of damage in other sieges, but it was only around 7 dwarves total. There had been 2 others, the first with no ranged, the second with a single boworc (who killed 3 crossbowdwarves.) This one, though, had about 15 crossboworcs. I did fairly well from my fortified walls, and killed off a bunch. But there was a problem: the rest of them were behind my fort at a point where I had only walls, not fortifications, due to a height difference. "OK," I thought. "I can build ramps up on to the walls. After all, one of my (4) marksdwarves has an artifact crossbow!" But no, it was not to be. Two died, and when I tried to get them to retreat, they held their ground. 6 other dwarves came up to grab their items, and 5 died instantly. The last one fell off the wall into the fort, and was constantly spamming "Urist McWounded cancels Rest: Interrupted by Orc Wrestler" for some stupid reason until he died later. Thinking that I could kill them with a little magma, delivered piping hot, Fuck the World style, I set up my pumps and windmill. Everything was in place except for the final wall to prevent it from spilling into my main fort and the final access channel to allow in the magma constantly pumped into my furnace area.
This was where things went even more completely and horribly wrong. In order to prevent myself from killing everyone, the upper one of two pumps had a door in front of it, connected to a lever. However, because the orcs would murder anyone who tried to build in their sight (which I wasn't quite stupid enough to do) I had to remove a section of wall in plain sight. I removed one section of wall in the tube that connected the upper pump and replaced it with a door. Orcs hadn't been able to destroy my test door for the lower magma flooding channel, so I assumed I was fine. I wasn't.
Turns out that they can destroy wood doors, but not rock ones. They got into my fort and basically started killing everyone. My four champion hammerdwarves killed only two of the 20ish remaining orcs before dying, and all I had remaining was a bunch of dwarves out in the main fort (who will be referred to as "Acceptable Losses" from now on) and about 10 dwarves locked into their bedrooms, which I always door off so that I can have a massive dining hall without overlapping. I figured that I might as well kill as many orcs as I could (they were just standing around in the main halls after killing everyone) and my one dwarf with a pick digs out the final magma channel. Magma zooms over to my secondary pump. My fortress starts burning.
Eventually, the orcs have all either died or left. My miner and a single peasant have died (I accidentally unlocked one of the doors in their wing without noticing) and my remaining 8 dwarves, in various states of woundedness, are walled off in the final bed wing after the door jammed on a piece of clothing. My glassmaker is in possession of a pick after a daring run just allows him to make it past the magma and orcs about to kill him and remove any hope of survival after a reclaim. All my food and booze is gone.
Currently, all but 2 of those 8 are dead, and 2 of the 5 migrants that arrived just in time to save my ass are dead to either smoke or orc wounds leaving them in bed with no buckets.
I think I need to build some sort of facepalm machine for myself.