Talassar is an Imperial Ocean World located in the Ultramarines' Realm of Ultramar in the Ultima Segmentum. Talassar is a planet of stormy seas and islands of rock. It has a single continent named Glaudor, which was the site of a major battle between the Ultramarines and invading Orks immediately after the Horus Heresy. Also considered a Feudal World, Talassar is ruled as a Dukedom by a Suzerain of Macragge and is the homeworld of the Void Tridents Space Marine Chapter raised during the Ultima Founding and tasked by the resurrected Primarch Roboute Guilliman with helping to defend Ultramar in the age of the Great Rift.
The notable Astartes commander Captain Cato Sicarius of the Ultramarines 2nd Company, was born in the city of Perusia and raised in the ducal household of Talassar, one of the most prominent of Ultramar's noble dynasties. Here he was trained in the arts of war at a young age. In battle, Sicarius prefers to wield a potent relic Power Sword from Talassar known as the Talassarian Tempest Blade in close combat.
An ancestral relic, this fearsome weapon takes its name from the planet's frequent storms. This weapon's energy field is so potent, and the blade within possesses a legendary sharpness so keen, that it has slain many a mighty foe in but a single stroke. Among his many honourific titles, Captain Sicarius is also the Grand Duke of Talassar.
Military of Talassar
Talassar provides its own self-defence through the Planetary Defence Force -- being part of the Realm of Ultramar, is not tithed and is not obliged to provide Astra Militarum regiments. However, it is so well-administered that it is nonetheless willing and able to provide regiments if the need arises. As the homeworld of the Void Tridents, it is now also protected by that Chapter of Primaris Space Marines' extensive fleet and fortifications.
- Castra Tanagra - An ancient fortress in the valley of Glaudor, this mighty fortress had been raised when Roboute Guilliman was young, its walls had withstood the fury of a greenskin invasion in the aftermath of the Great Heresy, and the Primarch himself had stood upon its walls in defiance of the savage invaders. Built in a circular fashion, with one of its four towers built into the cliff-face, Castra Tanagra was an elegant structure, its curving walls twenty metres high and built from blocks of black marble quarried from the canyons of Prandium. Every Ultramarines Neophyte of the Chapter was expected to make the pilgrimage to Castra Tanagra before his elevation to the fighting ranks, but the demands of war meant that few ever returned to study its majestic form. Its walls were carved with images from the first days of the Imperium, glorious, heroic frescoes depicting Astartes in their thousands crusading across the heavens with the Emperor at their head. Though Castra Tanagra was a holy place to the Ultramarines, the damage done to it during its last battle had never been repaired, for Roboute Guilliman had decreed that it forever stand untouched as a memorial to those that had lost their lives here.
- Captain Cato Sicarius - Commander of the Ultramarines 2nd Company, Cato Sicarius was born into one of Ultramar's noble dynasties, and also serves as the Grand Duke of Talassar.
- Codex: Ultramarines (2nd Edition), pg. 14
- The Chapter's Due (Novel) by Graham McNeill
- Warhammer 40,000: Rulebook (4th Edition), pg. 19
- White Dwarf (October 2017), "Eavy Metal - Create Your Own Chapter," pg. 118