Castra Tanagra is an ancient fortress on the ocean world Talassar's only continent.
In the aftermath of the Horus Heresy, the fortress was the site of a great battle between the Ultramarines, led in person by Roboute Guilliman, and a massive Ork Waaagh!. Afterward, Guilliman ordered that the breach in the walls never be repaired, as a monument to the Ultramarines who had died there.[1a]
After their induction into the Chapter, all Neophyte Ultramarines are required to make a pilgrimage to the fortress. Subsequent pilgrimages are encouraged, but few senior officers and veterans are able to make one.[1a]
During the Invasion of Ultramar in 999.M41, Marneus Calgar led the Ultramarines' First Company to the fortress after the battle-barge Caesar was shot down over Talassar by the Bloodborn. Although the fortress wall was still open, it was their best stronghold against the hordes of daemons being summoned by M'kar, especially when it was equipped with psychic wards that were empowered by Chief Librarian Tigurius.[1a][1b][1c]
After weeks of siege, the Ultramarines fighting to defend the breach in the walls, Calgar led the survivors of the First Company in a charge against M'kar and his daemon army.[1d] It was outside the fortress that the Daemon Prince was destroyed utterly, and the Invasion was defeated.[1e]
- 1: The Chapter's Due (Novel)
- 2: Rules of Engagement (Short Story)