I'd like to nominate my 1st Army (name, not descriptor) - a 9-dwarf squad consisting of 4 swordsdwarves, 2 hammer dwarves, 2 spear dwarves, and a axedwarf. I handpicked them from the 10 strongest dwarves in my fortress - all of them had the 'extradornilary strong' tag. They were my first dedicated fighting force for my current megafortress, they are all equipped with masterwork iron armor, and masterwork iron weapons (save the 2 hammerers, who have bronze hammers). As soon as I drafted them all, they went into a rigorous training course (didn't use danger rooms - they're sorta cheap), and when they finished they were all legendary in their assigned weapon, also legendary in armor user, shield user, and dodger. The training course did end up with one dwarf killed by a draltha, though... but worth it.
Not only have they been my first force, they've been my
only force for 8 years of fortress-running. I have never lost a dwarf in this fortress so far, nor has one ever been injured. not even my military. that's right.
Anyway... my 9 dwarves have defended my fortress from 8 years of sieges, including being outnumbered 20-to-1 during a siege, and still coming out of it. Well - not just surviving and fending off a 8-squad siege, but surviving without a single scratch/bruise on any of them. They got hurt more during training.
Special thanks to the axedwarf in the group, Aban Shaftgem - after a weaponsmith created a platinum battle axe I assigned it to one of my swordsdwarves, which then went a re-training in battle-axe 101. Once he was up to legendary, he was pitted against a Bronze colossus. solo. The rest of the army was down in the mines, fending off a FB incursion. He did this: