Loyalty and Treachery, Hard to Distinguish

"The XIII Legion's flagship is here, so their Primarch must be here too, my lord. We must inform the Primarch of Horus's betrayal—loyal forces need to rally."

Tassa said gravely. After the battles of Isstvan III and Isstvan V, the confirmed traitors were the Sons of Horus, Emperor's Children, Iron Warriors, Night Lords, World Eaters, Death Guard, Word Bearers, and Alpha Legion.

The loyalist Iron Hands, Salamanders, and Raven Guard had been crippled by the traitors' backstabbing, especially the Iron Hands' Primarch Ferrus, who was witnessed slain in combat.

The Imperium teetered on the brink of collapse. Though they didn't know why the Emperor's Warmaster had turned traitor, with the enemy at the gates, the remaining loyal forces would be picked off one by one if they didn't unite.

Lox also realized the human Imperium's fate hung by a thread.

He disliked this ignorant, backward Imperium, but there was no doubt it held humanity together. Humanity had reached the point of drinking poison to quench thirst—only this fierce cohesion could keep the species alive.

Just as he was about to order the cogitator to land on Calth, Iron Father Wayland raised an objection.

"No! We can't land now. We've already suffered betrayal from brothers—how can you guarantee the Ultramarines haven't turned too!"

Before the Drop Site Massacre, the loyalists sent to purge the traitors never knew the planned seven loyal legions besieging four traitor legions would become eight traitor legions backstabbing three loyal ones.

Even the Emperor's Children, who bore the Emperor's name as their legion's title and stamped the Imperial Aquila on their armor, could betray. Who could guarantee these Ultramarines, isolated in the galactic east and practically ruling the Five Hundred Worlds as their domain, hadn't turned?

Most Primarchs only recruited from their home worlds and cared little beyond the Great Crusade's campaigns.

But the XIII Legion was an exception. They recruited from every suitable world in the Five Hundred Worlds, making the Ultramarines the largest of all Astartes legions.

According to public intelligence, the Ultramarines had 25 chapters—250,000 fully armed Astartes.

Meanwhile, the Raven Guard and Salamanders behind Nykona and Tassa each had fewer than 100,000.

"My lord, I advise not sharing Isstvan V's intelligence with the Ultramarines until we ascertain their stance," Wayland declared loudly. Since their gene-father's death, the Iron Hands' trust in former battle-brothers had vanished.

Once sown, suspicion and doubt grow into towering trees.

"Ultramarines Primarch Guilliman has always been an ambitious one! He once tried to sway our father, but the wise Ferrus saw through it," the Iron Hand stated firmly.

"We need intelligence," Lox resolved.

"The cogitator can infiltrate that Gloriana-class Battleship's machine-spirit system or read the planetary defense grid's control systems, but that would expose us."

The cogitator's voice echoed in Lox's mind. Its high intelligence clearly sensed something akin to itself aboard that massive warship.

That was the Macragge's Honour's cogitator—or what they called a machine-spirit.

"Unless it's the last resort, we can't use the cogitator's infiltration ability. In fact, there are other ways besides boarding the Ultramarines' ships to gauge their loyalty."

If the Ultramarines had turned, their industrial worlds would be churning out war materiel for the betrayal. A sudden spike in industrial data could reveal plenty.

The Red Alert's surface quickly coated itself with an invisible distortion field, vanishing from its original position.

The Dark Age of Technology's stealth tech perfectly erased the starship's trace. On Calth's command center display, a tiny dot that had briefly appeared in that region suddenly vanished.

At that moment, on Calth's command towers, Adeptus Mechanicus servo-scribes and tech-adepts were processing data from thousands of transports and warships in orbit, missing the anomalous blip that appeared and disappeared.

Calth seemed to be hosting some major event. The traffic density before Lox and the others was staggering.

"Let me infiltrate the Ultramarines' ship. Stealth ops are better suited here. With multiple angles, we'll get more comprehensive intel."

The starship anchored in Calth's low orbit. Nykona, helmet back on, spoke.

In a sealed environment like a voidship, the Raven Guard's stealth skills shone. These infiltration-specialist Astartes could evade every pair of eyes and strike the target's heart.

"Good, keep this communicator. Use it to stay in stable contact with us."

Lox said nothing more, just pulled out a custom communicator. This little device could maintain stable comms within a star system, even under heavy interference, ensuring complete data transmission.

The cogitator had fabricated it using STC data from its database via matter-printing tech. Perfect timing.

Nykona sheathed two power swords at his back, grabbed his modified bolter, nodded to his battle-brothers, and vanished into the Red Alert's teleportarium.

His armor carried a teleport homer—activate it, and he'd be pulled back to the Red Alert.

In an instant, the ancient super-science sent the Raven Guard into the nearest battle barge in the spaceport.

"No need to plant teleport homers on targets. If our legions had this tech, boarding actions wouldn't be such a hassle," Wayland said excitedly. Currently, Astartes boarding relied on boarding torpedoes and teleport homers.

But if a teleport homer malfunctioned, the arriving warriors could get fused into the ship's structure, their molecules instantly mixing with the building's and killing them.

The teleportarium flashed again. Lox, Wayland, and Tassa materialized on the planet's surface. The remaining Iron Hands stayed aboard, ready for orbital drop support.

A concealed teleport beam touched down on Calth's ground.

"This is the south bank port of the Boros River. Numenas City lies across this wide river."

Lox, in combat gear, stared at the holographic projection before him. Beside him stood the Iron Hand and Salamander, their power armor swapped for Ultramarines patterns.

"Honestly, I prefer dark green. No such cobalt-blue scenery on Nocturne," Tassa's muffled voice came through his helmet.

"I don't like those arrogant Ultramarines cousins, but we need their strength now." Wayland turned his helmet toward a distant mortal soldier camp.

In that bustling camp, mortals operated engineering machinery and moved equipment. Most were shirtless, their muscular skin gleaming with a healthy bronze.

"Then follow me, my lords," Lox joked. From now on, he'd play a mortal attendant accompanying the Astartes. "At least they won't question my identity."

The odd trio—one mortal and two Astartes—was soon spotted by mortal soldiers in the camp. An old soldier with his dark blue uniform collar open, smoking under a tree, quickly straightened up and jogged over.

"My lords, Sergeant Bovi Herlock salutes you!"