-Formation of the Sith Remnant
Battle of Endor happened only 5 years prior. Immediately following the Emperors death the Empire became fractured at the seems. There was of course Sate Pestage's and then Ysanne Issard's attempts to fight the New Republic but after those leaders fell that group of the Empire was pushed back into Bastion with the Chiss at their backdoor. This faction of the Empire is known as the true Empire and they are ruled over by a Council of Moffs.
The Eraidu Authority and the War Lord Zsinj were soundly defeated by the New Republic and thus the New Republic own the largest swath of territory in the galaxy comprising most of the Hydian Way, Corellia, Mon Cal, and of course Coruscant. They have control of the Core but they barely venture into the Deep Core where it is rumored secret military installations of the Empire lay hidden away. Then in the old Sith space nobody cared much about but that was where the secret Shadow Academies existed that trained Dark Side users. This space contains Ziost, Korriban and Dromuund Kaas among other important planets to the ways of the old Sith. After Palpatine fell there was no way the Moffs were going to rule over powerful future Lords of the Sith. Taking quick actions leaders such as Darth Baum, Darth Yistark, and Darth Dusks took over the garrison fleets orbiting the planets and started to carve out their own tiny part of Imperial Space. They did it quickly and quietly and for the past 5 years been building strength and infrastructure as they knew they could not face the New Republic immediately on their own. But soon they will be ready to face the galaxy and they won't be forgotten anymore.
-Capture of Korriban
Korriban has been lost to us once again. Our homeworld the ancient seat of the Sith Empire and its authority now lies in Republic hands. They know how it affects our morale and are not quick to let us roam there again. They however underestimate the resolve and lengths we will go to reclaim Korriban once again. It gives us power and a battle over Korriban will undoubtedly go in our favor... if we have the numbers to back it up.
The Dark Council is missing many seats in its chambers. We need to find strong and daring Sith to fill these seats immediately. With a Dark Council fully at the helm our power will grow. After the fractures and civil wars within our Empire our military is not truly united and severely depleted. Therefore it is the Sith's will to conscript more troops for the cause and to overwhelm the Republic with troopers and Sith alike. It will be hard but we will strive ever onwards to victory.
Under the Command of Darth Yistark the capture of Korriban transpired without the New Republic being aware of who we were or what was happening. To them it was just a post and nothing of note but to us it was our home. Celebrations happened for weeks afterward.
-Campaign of Rhen Var
In order for our forces to get control of an Imperial Listening Post the Sith began to capture the world of Rhen Var. The campaign showed how weak the Sith were on campaigns far from Sith Space with supply lines and support being limited. Despite the small size of the New Republic garrison the effort expended was very high
-Deception at Yavin IV
The time had come for the Sith Remnant to make its move and reveal itself to the galaxy at Large with the capture of the New Republic's world of Yavin IV and the Yavin System. This would be a huge blow with the loss of the Jedi Academy and hopefully many Jedi along with it. Many attempts have been made to take the world and we would be successful. Everything went well until a surprise Stealth X-Wing attack a new weapon of the Jedi appeared and were able to take out several ships including the Flagship The Dark Mirage resulting in the Death of Darth Yistark. Then an Imperial Moff appeared in system with the intents of contacting the Sith Remnant. In the confusion only 66% of the Sith task force was able to return to the Ziost system. How this Moff will effect the war was to be seen