Despite the workings of the Sigillite and Valdor it was impossible for the foes of the burgeoning empire to not see. The ongoing war with Albia halts without the emperor to direct their forces against the tenacious enemy. Hy Brasil, the Pan-Pacific, and Merica begin to strike at their borders with the nascent imperium, as Orioc and Urartu lock themselves down building up their defenses.
Without the Emperor's brilliance the work on the Legion's are slowed and with the loss of the ability to make the custodians the Thunder Warriors are bloated in size with many new recruits being put under the blade to create the super soldiers.
The child was kept deep in the Himilazian mountains inside the fortress where he was born. He grew quickly in these troubled times, learning all skills. It is obvious where his talents lie though as he comes across field reports of a battle with Albia who was reclaiming lost ground with skilled assaults.
The young primarch drew up a detailed plan of a counter assault with contingencies for most responses the nation could devise. The massive tomb of a battle strategy was discarded by him though as he realized quickly the human and thunder warriors commander's wouldn't be able to follow such a plan. So he changed it alterations making the plan more compact, and shifting the few forces of the Astares already produced into a command role.
By the time of another push the imperial forces were prepared, Albia was pushed back the reclaimed lands lost again in a series of complex pushes. As the child commander of the golden palace learned of each proto legion's own natural talents he altered his plans and stratagems. Pushing back the forces that had seeked to take advantage of the leaderless imperium.
However he lacked the sheer charisma his father had, and his attempts to get Albia to capitulate were rebuffed. These old powers were too entrenched in the changing world to willingly give up their power when they withstood the emperor himself.
So he moved and the Sigillite aided in matters of the warp as the young primarch lacked talent in that area. This time where the imperium shifted under a new rule that the child, Roboute Guilliman some would call him. His Legion, the first of them all to grow into that name, is like all the Astares in this era commander's before all else.
Each Astares is an impossible physical combatant of skill and strength unopposed by nearly all but to Guilliman the young Emperor ascendant it is their mind that is the greatest weapon. Their skill in battle makes them front line generals guiding men, their mind is the engine that moves war forwards.
Under this weight Albia is broken tower cities claimed under the might of the empire. Thunder warriors, and the army guided by superhuman minds.
Slowly but surely all corners of Terra are grasped by the hand of the imperium. Guilliman without the Emperor's understanding does not paint the Imperial Truth in the same way. Where the Emperor had meant it as a tool against Chaos, the child leader wasn't told in detail the nature of the warp. So he took the truth as a tool of unification, religions are not a dangerous thing but rather some can twist the foundations a nation requires.
After all, what empire can survive when its citizens put an unknownable godhead above the good of the nation. How can humanity survive this cruel galaxy when one puts the good of their faith above the survival of their kind? So the Imperial Truth lives on as a rejection of fanaticism rather than a full rejection of religion. Some small cults remain regulated and watched by the burgeoning imperial bureaucracy. Given leeway in their faith, and a promise of minimal interference the antarctic state of Orioc willingly joins the collection of member states with semi autonomy inside the empire.
Merica and Hy Brazil fight on but the despots of Hy Brazil give in as imperial forces reach their homelands. Merica is left against a well positioned army that flows against it from all sides and is crushed. Urartu is a small techno barbarian state, the mountain citadel is not too far from the capital fortress of the empire whatever plans say fit to ignore them have been lost. In short order they are assaulted by forces of the Astares as not all legion's temperament were a perfect fit for Guilliman's strategy. These forces were deployed Astares of the 8th, 19th, and 20th legion were unleashed on the city state. A war in the shadows was not what their walls had been built for and as the leaders of Urartu find their corpses impaled on the walls their moral bleeds like water and they soon surrender.
The final battles of Terra draws neigh as the Pan-Pacific Empire crumbles. It's few allies dead, it's people discontent with their tyrant. Each day draws the end of the last independent nation of earth nearer. The blade of the new Emperor drawing closer.
However deep in the Himilazian mountains another battle rages unseen. The handsome man of impossible size clad in golden armor in memoriam of his father pours over papers each document drawing the same conclusions.
"There are a million soldiers in the Thunder Warriors. The lightning banner was not made by my father to leave this world." Valdor nodded, and the Lord of Terra was reminded that the Custodians had not engaged in battle since the death of the Emperor, his armor painted black as he and many of his fellows had done in their grief.
To Guilliman, the thirteenth primarch, the loss of the Custodians as a fighting force was never felt as he had grown understanding them only as guards, advisors, and keepers of the eternal crypt. He had not ignored such a force though rather weaving the artistry of the Emperor into the highest level of the growing imperial government.
Valdor was his personal advisor but for all those who would aid ruling the empire the custodians were to be an ever vigilant eye that guided them. Super human minds serving as advisors. "They were only a stop gap as the Astares program wasn't ready even halfway into his campaign, increased aggression can be delt with but this deterioration across their bodies and mind up to a 90% fatality rate in a ten year period. Worse as they decay likely they will go berserk."
So the unification draws near all of earth will soon be granting fealty to the new Emperor who is locked up in his fortress capital determining the fates of a million warriors whose blood and sacrifice built the foundations for an empire to come.
[]Bled
New production will be hauled and the Lightning Banner will be seen in battles across sol as the front line and shock troopers. They will be given a chance to die off with honor.
[]"Heroic" Stand
History will say that the last of the Thunder Warriors died in the final siege of the Pan-Pacific Empire. History of course is a lie, but a kind one. The Thunder Warriors will be sent in to deal with the final fortress cities of the hostile Empire and their will be no survivors.
[]Fixed
The Thunder Warriors are theoretically cheaper, if effort is used and research of the Custodians and Astares is used they could be hypothetically fixed, it will slow down production of the Legions but it will give the imperial army elite shock troopers.