The most populous system in the Prastian straits is protected by the guns of XII. A fortress world in the system's outer reaches, it is home to millions of guardsmen drafted from V and IX and dozens of defence lasers pointed at the stars above. These potent weapons are backed up by sixteen torpedo platforms in geosynchronous orbit and thousands of mines sown in deep space. Patrolling the shipping lanes are the vessels of the Colossal Intrasystem Monitor Fleet, its ships covered in banks of Mars pattern macrocannons. The system's own defences are strong, a point that Lord Governor Elcam is keen to emphasise at court in the Carthax sector, but even he is glad for the support of the Imperial Navy in deterring pirates from his system.

The fortress world is also the site of a large orbital Imperial Navy facility known as the Prastian Knot. This space station is the permanent base of Patrol Group Falchion, a Battlefleet Carthax element deployed to patrol the Prastian Straits. Their current objective is to contain the Schest of the Ter system and pirates of the Maalachai system, and a number of duels have been fought in recent decades. No telling damage has been done to either side, but Commander Sarygossian of the Knot believes that a major incursion by either opponent is not far off.

Patrol Group Falchion comprises the light cruiser Belle Tigris, the frigate Blessed Infamy, the destroyers Maxim and Chaste Maiden, and the converted carrier Pilgrim's Revenge. Command crews are often fresh out of naval academies, something Commander Sarygossian believes to be foolish in light of the dangers that are amassing within the Straits.