GATE:THUS IMPERIUM FOUGHT THERE(WH40K)

Opening of Gate in throne world

In M43, Emperor finally resurrected and beat the s**t out of every other faction and reconciled with all the 19 primarch (yeah alpharius and omegon are two different primarch here).
Currently, the situation is that tau are exterminated to the last one as a contigent of custodian with the orders from the emperor himself take the charge , although some reports indicate that of those few custodian one was particularly happy especially when he killed comander shadowsun.

Necrons are put back into their sleep thanks to the enormous amount of warp usage by emperor and magnus in finding the sleep button created by c'tan and then pressing it (also magnus did nothing wrong and this time the emperor has agreed)

Tyranids are exterminated with the help of iron warriors who are the only legion that were able to capture an entire tyranid hive ship and used it to destroy each and every tyranid presence in the galaxy

Well the Eldars and Dark Eldars are subdued by emperor and he used the original plans of webway (not the one that eldars claimed they have created but the one that are literally made by the old one )
To repair the one created by emperor
(and emperor definitely not use it to bring eldar prostitutes into imperial palace)
Orks well are orks and they love being orks so the emperor just throws all of them out of this galaxy into DOOM so that DOOMSLAYER/GUY can get a bit more fun.

And lastly, 4 GODS OF CHAOS
,Emperor using super massive fucking OP psyker Power controls the realm and created a massive wall between realm of gods and materium and now is rehabilitating all 4 of them.
As all the xenos are put under constant observation emperor started looking at future and bring changes in imperium also all the legions are restored although many people questioned this decision but emperor know that he has achieved victory but there is one more thing that is coming which will change everyone's mind and multiple relams are going to tremble.
For now Emperor was being emperor he make many upgrades in arsenal of space marine and imperium in general and biggest contribution in this was of Perturabo who improved almost everything from armor and weapons  of guard to advanced space marine suits and even bigger ships and advanced infrastructure projects across the imperium and as a gift to emperor on his birthday he presented emperor a flagship which was much bigger than the Phalanx and to everyone surprise he commissioned and created 19 one for each primarch except for Rogal but he instead helped in improving the systems of Phalanx which made it 45% more optimal
As emperor and other primarch were debating in round table meetings over what to do next a custodian entered the room and deliberately said 'MY LORD YOU NEED TO SEE THIS' every one rushed to see what just happened but emperor was calm as if he knew that this was about to happen.When they rushed outside they see that a massive gate like structure has appeared right in middle of streets .As people and other creatures who were carrying medieval weapons and armor rushed out of the gate and attacked people gathered to see the palace , custodian rushed to kill them but Emperor halted them and used his power to freeze them all and told the guardsman to round them up and capture them them after few hours of debating over what to do next the Emperor brought the prisoners to  the war council and read their minds and learned about these otherworldly humans and discovered that they come from a place called 'Falmart' and are subject to an empire name 'Sandera' with the brief thinking Emperor said ' We are going to unite this world from which these invaders have come into the Imperium of Man '.
As plans were drawn out and logistics department was preparing for this offensive strike Emperor disclosed that after bringing this planet under their domain , He would launck another Great Crusade in that galaxy.

In the first wave :
Dark Angles and Lion'El Jonson
Thousand Sons(Blood Raven)and Magnus the Red
Imperial Fist and Rogal Dorn
Iron warrior and Perturabo
2 Million Guardsmen from different regiments
1 Order of sisters of battle
200 Custodian
5 Titan legion
8 million reserves that will stay on Terra

Logistics Departmen reports:
15 million human grade power armor
15 millon manportable Lascannon
300,000 Tanks and S.P.G
150,000 Artillery pieces
2 Castigor Class titans
5 Emperor Class titans
15 Medium class titans
20 Reaver class titans
45 Scout titans
And 75 Knights of different class
Along with 2 fleet i.e-
25 Battleships
35 carriers
45 escort carriers
1 Flagship
105 Different class of cruisers
140 Different Destroyers
290 frigates and Corvettes
345 Escort Ships

Emperor appointed Lion as the leader of the task force
Gulliman as Master of logistics
Dorn and fortification engineer
Magnus as Master of all the studies and surveys
Perturabo was given the charge of Infrastructure and city development.
Fulgrim , Horus and Sanguinius as apparent peace and relations builders
Konrad is taken for Unconventional warfare.
As the Scouts have recon the area and mechanicum have build webway to bring ships .
As departing for the Falmart Emperor made the speech 'My SONS , MARINES ,GUARDSMEN ,CITIZENS OF THE IMPERIUM TODAY WE ARE GOING TO EMBARK ON A JOURNEY THAT WILL CHANGE THE COURSE OF BOTH THE WORLD WE WILL SEEK ANSWER AS TO WHY WE WERE SUBJECT TO THIS ATTACK AND WE WILL CLAIM THAT PLACE FOR THIS GLORIOUS REALM CALLED IMPERIUM OF MAN '
The crowd cheered the Task force as they started to cross the Gate.