Thracia

Thracia is an Imperial world on which the Ultramarines Fourth Company fought during a Chaos-fuelled rebellion in late M41. No segmentum, sector, system or coordinates are recorded for it.

Captain Idaeus led the company to destroy bridges that rebel forces, reinforced by Night Lords, might have used to outflank the Imperial Guard. At Bridge Two-Four he gave his power sword to veteran sergeant Uriel Ventris and detonated the remaining charges, dying in the blast.

Ventris was confirmed soon afterwards as captain of the Fourth Company. Thracia is remembered as the place where command of the Swords of Calth passed from Idaeus to Ventris.