It was not only the Sons of Horus who were rushing to assemble at Ullanor; the Word Bearers were as well. As the backbone of the rebel forces, the Iron Warriors and Death Guard were likewise taking their own separate paths.
They had not chosen to travel alongside the Vengeful Spirit. It was not merely because of suspicion and mistrust, but because they had to take different routes to regroup the Legion forces scattered along the way.
Everyone knew that the heart of the coming battlefield would shift to the Sol System. Perhaps the loyalists and rebels would settle everything upon humanity's homeworld—Holy Terra.
As such, every Legion had to bring itself into peak condition. A tiny detail might determine the fate of the galaxy.
The ancient tale of a lost horseshoe nail costing an empire was still passed from mouth to mouth among humanity.
Especially the Iron Warriors. Their main body of Astartes and mortal auxiliary forces had remained at the very rear of the rebel lines, holding back the Lord of Macragge's frenzied assault.
The Ultramarines had gone completely mad.
Their defense was arduous. Guilliman was charging desperately toward Terra. This Thirteenth Primarch, absent from so many major battles, seemed to have little presence, yet he had in fact played an irreplaceable role.
Because of him, the rebels had been forced to divert vast numbers of troops to hold their rear.
Especially the Fourth Legion. If the layered defenses built by the Iron Warriors had not bought enough time, Horus's rebels would have long since been stabbed in the ass by the Ultramarines pouring in like mountains and seas.
According to reports from the front, the Lord of Macragge had assembled at least over three hundred thousand Astartes, along with mortal auxiliary armies numbering hundreds of times more.