Despite the sheer scale of the war raging now, most war zones were actually confined to a tiny area around the Eye of Terror. Overall, the Milky Way Galaxy was quite peaceful, comparable to the thousand years of peace after the Horus Heresy.
(The Primarchs had still been around then. After they disappeared, Sigismund cut his way through every enemy.)
One could say that, as long as the Alpha Legion and the Crimson Tide stayed out of trouble, the galaxy remained fairly stable.
Even the biggest pirate bosses were on their side. How could things not be stable?
As long as Guilliman pushed the front to the Eye of Terror's first defensive ring-the belt of fortified planets beyond Cadia, surrounding the "Eye of Terror's Gaze Corridor"-the Imperium would have the situation in hand.
The IV Legion's chances of successfully springing its ambush were steadily declining.
Tzeentch had originally thought the Word Bearers could inflict massive losses on the Imperial Expeditionary Force, leaving the half-crippled IV Legion strong enough to confront the Lord Regent.
Instead, the Crimson Tide's sweeping feint offensive through the surrounding regions not only delayed the Expeditionary Force considerably, but also convinced it that too many enemies were nearby. It paused to regroup and summoned more troops.
Chaos was getting frantic. Come on, hurry up and attack me! If you don't come, I'll kill everyone!
Chaos cultists slaughtered people across the worlds they had conquered around the Eye of Terror, broadcasting the news with astropathic signals hundreds or thousands of times stronger than normal.
The Imperial forces were tied down, but the Crimson Tide refused to accept that. Their mission was to lure Imperial forces into reinforcing a Sanctuary World, yet when their scouts checked, this was all they had sent?
Furious, they concentrated their forces and actually