According to historical records, on the eve of 2K, an isolated war broke out on ancient Terra.
Because so much time had passed, the surviving records were incomplete. Guilliman knew only that the two sides had fought in a jungle, and that the phrase repeated most often was "the trees are moving."
Perhaps it was because they belonged to different factions, or perhaps for some other reason. In any case, the two sides used different weapons. But that wasn't important. What mattered was a famous old rumor from history.
According to the rumor, during the fighting, one side's soldiers suffered a string of Machine Spirit malfunctions because of their weapons: some backfired, others jammed. The soldiers cursed their own weapons and rushed to seize the enemy's instead, until both sides eventually equipped themselves with them on a large scale.
But a rumor was just a rumor. The two sides used different ammunition, so how could they simply drop their weapons and pick up the enemy's? At most, they might use one in an emergency. If they weren't careful, their own allies could easily shoot them dead.
The truth was that it was human error. The weapons jamming had nothing to do with the guns themselves—or at least, that was only a minor factor. The main problem was the ammunition.
Guilliman had always enjoyed these amusing snippets from ancient history, reading them as bedtime stories. Whenever he came across some ridiculous stunt pulled by the ancients, he would smile knowingly and remark, "Look at those Terrans. What a bunch of losers. They're no match for Macragge!"
But Guilliman wasn't laughing now. Nobody could be happy after losing their own butt.
Seeing those two bastards using his butt for research while he floated in midair with only his upper half left, supported