The strategium of the Samothrace could be sealed off from the bridge and its distractions of moment-to-moment demands. The doors were closed now, turning the chamber into a sanctuary of war governance. Here the theoretical was tested. From here, the practical issued. The dome of the strategium was lower than that of the bridge, the darkness of its stone illuminated by a hololithic projection of the regional star chart. The relative closeness of the walls and the constant presence of the immediate battlefield focused the mind.

The star chart was a complete blank during the transition through the warp. That was the one note of grace as the operation continued to break down. Guilliman took in the essentials of the onrushing, overlapping reports. The hololiths on the tacticarium table were a patchwork of approximations, guesses and darkness. It mocked Guilliman. It was the evidence of his campaign’s theoretical devolving into a pointless exercise, one that no practical could salvage.

He had divided his fleet into strike forces, each powerful enough to annihilate a system. He had ordered tight formations. If the warp storms pulled the ships away from each other, their jump was to cease and the strike force reassemble before a new attempt was made. The wrenching apart was already occurring, and Guilliman’s cohort had barely started this jump.

The deck heaved as the Samothrace ploughed through the storm. The Ultramarines officers gathered in the strategium did not shift with the motion. They were solid as marble columns. From the corner of his eye, Guilliman saw a ripple crawl down one side of the doorway. The materiality of the ship was less stable than his sons.

‘Theoretical,’ said Titus Prayto, speaking over the droning vox-speakers solemnly announcing the formation’s disintegration. ‘The increased resistance is evidence that this route is the correct one.’

‘An inviting theoretical,’ Guilliman told the Librarian. ‘One dangerously close to wishful thinking.’

Prayto nodded once. ‘Admittedly so.’

‘And we have no choice but to verify it,’ Guilliman said. ‘Shipmaster,’ he voxed Turetia Altuzer, ‘end the jump.’

‘So ordered, my lord.’

Deep in its core, the Samothrace shuddered. The tremor swept along the length of the ship. It passed under Guilliman’s feet. He grimaced in sympathy for the great vessel’s pain. A moment later, there was a change in the air, a more assured reality. They had returned to the materium.

After a series of flickers, the star chart appeared in the vault again. Guilliman glanced up.

‘Apologies,’ Prayto said. ‘That was wishful thinking.’