The scale of the full-scale counter-offensive launched by the Tyranid Hive Fleet was evident from orbit; the dense spore cloud was like a colossal wave sweeping across the planet.
However, in the Plantidium system, this colossal wave crashed against an invisible Wall of Sighs.
The joint forces composed of the Helldivers and the various Astartes Chapters showcased the pinnacle of human military might to the entire galaxy.
When they attacked, they were the Spear of Longinus, capable of slaying gods; when they defended, they were the impregnable Wall of Sighs.
The swarm was crushed against the defensive line of steel and bolter shells. Subsequent forces even had to advance over mountains of their own kind's corpses, only to become new corpses themselves.
Marneus Calgar was in good spirits—it was impossible for him not to be, as the battle lines were steadily advancing, and everything the Tyranids did was being pulverized under the iron hammer of humanity.
Occasionally, the data in the battle reports gave him pause: even with all their preparations, the human attrition was terrifying.
For instance, Plantidium had a daily loss rate of nearly a thousand Leman Russ tanks. At this rate, by the time the war against the Tyranids ended, there would likely be millions of Leman Russ tank wrecks across the planet.
Faced with such reports, the only party likely to be happy was the Adeptus Mechanicus—they hadn't received orders of this magnitude in ten millennia.
It was precisely because of the terrifying sacrifice of the mortal forces that Astartes casualties were reduced to a level that could even be described as "trifling."
Under this combined effect, Calgar became even more resolute in his decision to unite the Chapters against the enemy and deepen the alliance with the Helldivers.
Because even he wasn't sure if the Ultramarines and the Ultramar Auxilia alone could withstand the endless tide of the Tyranids without the support of other Chapters and the sacrifices of the Helldivers.
Even if they won a pyrrhic victory, what devastating casualties would the Ultramarines suffer? And to what extent would the homeworlds of Ultramar be damaged?
At the very least, it wouldn't be like it was now, with the flames of war confined tightly to Plantidium, and the Goddess of Victory already having mounted humanity's war chariot.
Calgar believed that even if the Tyranids invited all of the Goddess of Victory's distant relatives, they couldn't persuade her to switch sides.
So, overall, Calgar was still in good spirits. In fact, he now even had leisure time to listen to music.
Music echoed in Marneus Calgar's command chamber. It was a grand and solemn symphony, filled with a sense of Imperial power and order, as if it could transport a listener back to the distant, glorious era of the Great Crusade.
Just then, a Servitor glided silently to his side and reported in a synthesized voice: "Chapter Master, Governor Robert of Perditia requests an audience."
"Let him in," Calgar waved his hand, signaling the Servitor to lower the music volume.
Soon, Robert, wearing the Governor's uniform, entered. His face revealed little emotion: "I didn't expect to find you listening to music, Lord Calgar."
Calgar displayed a rare, easy smile that somewhat tempered his usual sternness. He gestured to the ornate device made of unknown crystal that was playing the music:
"A tribute from a Sector Governor. He claims this sonic crystal itself is a relic from the Lost Age. The music recorded within is The Stellar Ode, a masterpiece by one of Holy Terra's greatest composers of the M30 era, Ludovico Macadolian, performed by the legendary musician Hesiod. I've been busy, so this thing has just been gathering dust. If you like it, I will give it to you now."
Robert shook his head honestly, his gaze not lingering on the artwork: "Forget it, Lord. I don't understand music, and I haven't heard of any of the names you just mentioned."
"Haha!" Calgar burst into hearty laughter. "Honesty—that is an excellent quality. I am tired of nobles who pretend to be knowledgeable in fields they know nothing about."
After the laughter, the atmosphere returned to the main point.
Robert's expression became serious: "Lord Calgar, I have come to discuss the post-war reconstruction of Perditia. My soldiers... they have given everything they could for the Imperium.
I hope that after the victory, their home will receive the reward it deserves, and not be forgotten by the Imperial bureaucracy."
The easy smile vanished from Calgar's face. He could clearly feel the sorrow conveyed through the words.
Even as an Astartes, Calgar was affected by this raw emotion. The grand symphony in the command chamber suddenly felt inappropriate, even grating, in that moment.
Calgar nodded solemnly: "Rest assured, Governor. I guarantee you, upon the honor of the Ultramarines, that after the war I will personally dispatch the most professional planners and Tech-Priests, and mobilize Ultramar's resources to aid Perditia.
I cannot promise to rebuild it into a Paradise World, but it will meet the average livability standards of the Five Hundred Worlds of Ultramar."
This was a promise of enormous weight. Robert looked deeply at him and rendered a military salute: "I thank you on behalf of Perditia."
"You should not thank me," Calgar stated gravely, "but your warriors. It is their sacrifice that has earned this opportunity for their home."
Robert lowered his hand, paused, and then suddenly asked: "One last question, Lord Calgar. In your opinion, what truly makes this piece of music so pleasing right now—is it Ludovico Macadolian, who composed it, or Hesiod, who is performing it?"
Calgar froze, completely failing to follow the Governor's train of thought. The question was too disconnected from the previous topic, almost entirely unrelated.
He pondered for a moment before giving his most straightforward judgment: "It must be Ludovico Macadolian. After all, if he hadn't composed the piece, the performer would have nothing to play."
After hearing the answer, Robert showed a knowing, meaningful smile.
"Then you must be careful with your performance, Lord. At the very least, you should give Ludovico Macadolian cause to praise you."
With that, he saluted again and turned to leave the command chamber, leaving Calgar alone, frowning, completely bewildered.
For a long time afterward, Calgar repeatedly pondered the meaning of Robert's cryptic final words, but he never gained any insight.
It wasn't until the Primarch Roboute Guilliman awoke from stasis in 999.M41 that he finally understood.