Ungatt Trunn was the brother of Verdauga Greeneyes and the uncle of Tsarmina Greeneyes. His father, King Mortspear, ruled a highland kingdom, but Ungatt Trunn had no desire to rule it. He was a powerful warlord who led a vast army of vermin known as the Blue Hordes, because they painted their fur with blue dye. Trunn thought his Blue Hordes (rat, weasel, ferret, stoat, fox, wildcat) to be superior to all others, and sought to conquer or destroy all other creatures he considered "inferior". He would use intimidation - derived from the sheer numbers of the Blue Hordes - as a weapon. He and his hordes attacked the mountain stronghold of Salamandastron, where the old Badger Lord Stonepaw and his fighting hares lived. Trunn succeeded on conquering the mountain and killing Stonepaw.
Ungatt Trunn was completely ruthless and punished his followers severely when they failed him. This mostly was torture or slavery that led to death. One of his victims was an old fox named Groddil, who was formally his advisor and seer. Groddil was made a slave, and abused, but later escaped.
Ungatt's rule of Salamandastron was short-lived, as he was put under siege by Stonepaw's son, Brocktree, and his army of woodlanders. It ended out as a one-on-one duel between Trunn and Brocktree. The wildcat's weapons were a sword, net, and trident. Brocktree eventually defeated his opponent by grabbing Trunn and snapping his spine. The wildcat's body was thrown into the sea, but he was not yet dead. He washed up on the shore a few miles away, and struggled to reach help. Then he saw Groddil the fox standing above him. He begged for help, but instead Groddil pushed his former tormentor out to sea, where Trunn presumably drowned.