Chapter 1: The End of a Heresy and The Reunification of An Empire.
(The year is M37, the heresy had been happening for 12 years. Many of the Emperors children had betrayed him, had fallen to chaos. These heretical Primarchs who had fallen to chaos and rebelled were Angon, Fulgrim, Mortarion, Lorgar Aurelian, Konrad Curze, Alpharius Omegon, and Perturabo. There was also a mechanicus traitor by the name of Kelbor-Hal. These Primarchs rebelled against the Imperium, and the Emperor for the powers of Chaos. This started the heresy in M37 and lead to 13 years of conflict and death. And now with the death of Angon, and Fulgrim, along with the routing and the retreat into the warp of Mortarion, Perturabo, and Kelbor-Hal, leaves us with Alpharius and Konrad Curze left. And this brings us to Horus (Luna Wolves) and Leman Russ (Space Wolves) with their Legions fleets supported by the Imperial Navy, warping in to Alpharius' last known location at the siege of the hive world of Lonmar. This is primarily from Horus' point of view. I may make a 1.2 in the future doing the majority from Leman Russ view as well as more on the siege.)
(Luna Wolves navigator aboard Horus' new flagship, the Heavy Dreadnaught Indomitous) "Primarch Horus we have completed a Primary scan of the planet and the surrounding area. We are currently 10,000,000 miles from the planet currently. We have not located the enemy flagship but we have approximate numbers of ships and their location participating in the siege. Primarch Russ has already engagaed much of the rear vanguard and is pushing to intercept the ships bombarding the planet. The navy is preparing to drop Guard onto the planet, and Leman Russ is dropping astartes for support." (Horus) "I see. We will engage the fleet besieging the planet and drop the 4th company on the planet for support. Keep trying to find Alpharius, we will break off to engage if we locate him with Russ." (Navigator) "Yes Primarch"
And thus the battle ensued in space and on the ground. The fleet besieging the planet was slaughtered by the Luna Wolves and the Imperial navy and the battles on the ground grew bloody, but ended with the death of the Alpha Legion field commander to a Luan Wolves Vanguard terminator squad and the subsequent slaughter of the few forces remaining on the planet. (With the terminators wielding the mkXVII Mobile heavy Cataphractii Mars pattern armor and mkVII plasma bolters, increasing the durability of the armor and substantially increasing the mobility of it.) With the battle in space continuing and the battle on the ground won, Alpharius warped in with a large amount of his fleet and traitor imperial navy to try and eliminate the forces breaking the siege. However his intelligence failed him. He failed to be informed that Horus was at the planet with Russ.
(Luna Wolves navigator)"Horus the flagship has teleported in shall we engage? (Horus) "affirmative, tell Leman that we plan to board the ship. Have the rest of the fleet engage the traitors and make sure first company is ready." (Navigation) "yes primarch."
Now the Luna Wolves and Space Wolves with the Imperial Navy engaged the traitor fleet. At the same time Horus was approaching Alpharius flag ship attempting to board with his first company. And as he cut his way through the fleet, he boarded the ship. He and his first company slaughtered their way through the alpha legion attempting to get to the bridge. Cutting down any heretics that stood in their way. The first astartes to enter the bridge were immediately killed by Alpharius along with a lot of the terminators in the hallway pushing in. And then Horus barged in, slaughtering most of the traitors in the room. (Horus) "Hello, Alpharius, brother. We meet yet again aboard your ship, only this time you have betrayed us." (Alpharius) "Yes I have, you worship the emperor, wrongly. He has wronged all of us Horus. He betrayed you. He lied to you. The way is chaos, brother. There is still time to join, it isn't too late. We are going to retreat back into the warp, after we raze this planet. Join us and leave the Emperor." (Horus) "I would never betray my father Alpharius. I would never leave him, leave the imperium for chaos. You will die Alpharius, I'm sorry brother." And with that Horus struck, and the battle ensued on the bridge with the battle raging around them. Leman Russ had at this point boarded the ship and was heading to the bridge, along the way encountering skirmishes between Luna Wolves and Alpha Legion. As he headed to the bridge, the battle continued to be fought.
Leman, arriving at the bridge witnessed the battle with Horus enraged, having already wounding Alpharius multiple times pressing on. Leman charged in, joining Horus wounding Alpharius severely then leading to Horus cutting him down. Alpharius was dead as the battle continued to rage on. They left Alpharius ship, returning to their ships and again rejoining the fight, destroying Alpharius ship and most of the Alpha Legion ships present. With the battle done, the siege broken and Alpharius dead, they had completed their mission.
At this same time, Magnus the Red of the Thousand Sons, Rogal Dorn of the Imperial fists, and Roboute Gulliman of the Ultra Marines, were hunting down Konrad Curze and his Night Lords. They attacked, beating the vanguard back and attacking the main fleet around the world of cadia near the eye of terror, but Konrad was able to escape into the warp with alot of his fleet intact. The remnants were destroyed. This was the near the end of the Heresy.
With most of the traitors dead or retreated into the warp, the Imperium reunited. At this time with most of the traitors gone, the Emperor ordered the fortification of the planet Cadia, near the Eye of Terror and ordered that any and all heretics hiding out, or present would be killed on sight. The webway project continued and as always, the technological advances went forward. The imperium still being invaded by all manner of horrors, stood strong and defiant to the wills of the chaos gods. (Addendum: I will do a lot more of the heresy after I finish the main story, I do plan on finishing the story not sure how long it will be though. I will also do more inter-milky way galaxy stuff as well after I finish this.