I took on the third siege in three seasons as well and they were promptly routed again. One dwarf lost - child of a marksdwarf took a close personal look at warfare and got a demonstration on how swords work. My "no lines of sight" architecture helps keeping soldiers alive by preventing them from being swarmed or shot at, but is a serious danger to the ridiculously long-leash civilian AI - they'll keep trundling forward about twenty steps after a hostile has come in sight. I've never had more than one bed occupied in the hospital at once, there's basically no room between "alive and healthy" and "very, very, very, very dead".
To show off the power of highly-skilled militarydwarfs in good equipment (all masterwork steel weapons for edged, steel and high-quality bronze armour), the last two goblin-and-troll sieges were held back by a military consisting of four legendaries and two middling-to-high-skilled hammerdwarfs, with a makeshift archer squad of six heads as backup which saw no to very little action. There are 120 beards on site, almost half of which are children. Ten adults are always-training military, six of them sufficiently skilled to face combat. About thirty dwarfs total have died, fifteen of which were burned by a single tortoise fiend law-giver of the goblins, and three more were stricken by grief over the lives lost in that battle.
Meanwhile in the glacier fort...
the preliminary test of the beefed-up minecart grinder has been promising - minecarts will not lose their load when colliding with a goblin in such a fashion that the gobbo is sent flying. I hope this means a minecart can reliably flatten anything that weighs less than ~2/3 of minecart+load: a load of 5 native gold boulders accounts for just under ten tons, which might be adequate to move a jabberer.
Getting dwarfs married has also paid off, seven children were born in the last year and a half, and fortress population is up by six, just short of the fifty required for a mayor.
The one loss was once again by glitches and general dwarven stupidity, combined with lack of attention by the overseer: yet another goblin, this time a snatcher, managed to enter the fort through the solid ice. I've no idea how they do this, either the spawning screws up when the spawn point's too close to the glacier/tundra biome border and one unit or several end up spawning "on solid floor" inside the glacier, _or_ they somehow dodge traps/carts through the floor. Anyway, the goblin was spotted and chased by war bears and jumped into a cage trap. Little did i know and even littler did the dwarfs bother to alert me to the fact that the goblin had already snatched a ten-year-old child, who was now stuck in a bag in a cage. I only noticed when the child was announced "missing". I _could_ have realised that there was something up when some rat weed seeds were displayed in a goblin cage - the damn stupid dwarfs had given food and water to the captured child, but of course only once, thanks to the stupid prisoner food bug. Incidentally, the snatching bag was considered a "rat weed seed bag" by the game, and i had a dickens of a time getting the corpse out there - corpses in a container are not collected normally, and bags qualify.
I later killed that goblin by caving a piece of floor on top of her - i wanted her encased in ice, but forgot that ice forms immediately below the drop location when filling a pond. I would even have let her live if she hadn't glitched her way into the fort. I have since installed a bunch of weapon traps at bottlenecks within the fort proper, to hopefully get a better handle on glitched/teleported enemies.