Tireme Airship Talos

Twin sister to the flagship of Imperial Alexandria's trireme fleet. Prior to the development of the trireme, Alexandria's air force consisted of zeppelins and wooden-framed aeroplanes. The great empire needed to flaunt a new weapon in order to be taken seriously again by the likes of Karaden and Sondor, both of which had glossarian-type airships. The Talos and her sister ship, Argo, provided the perfect demonstration when they broke the defenses of an enemy stronghold to the south, enabling the Alexandrian army to rush in, and by doing so, secure a huge territory. Following their initial success, Argo and Talos provided the template for all of Alexandria's new capital airships. 

I've already spoiled the story by sharing the second half of the final chapter of book 5 on my blog, so here's the TL;DR version: Captain Maria Beltova commandeered the ship after being marked for death, and then used it to allow the Aeronautical Development to escape from the Zaphnora.  The latter rammed the Talos and broke the ship in half.  Anyone who survived the crash ended up dying of hypothermia when the wreck plummetted into the icy waters below.