Ben set up at Lady Phasma's home, Starkiller Base, where Snoke and Hux, amongst others joined him. Ben then issued a declaration confirming that he had changed his name to Kylo Ren, to remove the link to his family. Along with his intention to remove the Skywalker line from the throne (even if his right to the throne arose through it).
A couple of weeks later, whilst Kylo was gathering his forces and strategising, Poe Dameron was captured making enquiries in Niima village. Kylo interrogated him himself, and that was how they gained the intelligence that foreign forces were gathered together to come to Luke's assistance now the main Alderaanian army had come across to Kylo under Hux's command and all he had was the house guards of loyal lords and ladies.
That was how Hux managed to take the foreign forces entirely by surprise, decimating Luke's reinforcements. It was a huge success, that Hux made sure everyone was aware he was responsible for.
Unfortunately, the next battle was at Starkiller Base itself and was a complete disaster. Poe and his traitor friend had infiltrated the building and set it ablaze, and in the confusion, Han Solo led an assault. Kylo ended up in one to one combat with his own father. He thought that the moment when he plunged his broadsword into the man that sired him, that it would ease the hurt and make him feel justified, but instead Kylo felt like there was a huge hole inside him, and that maybe he didn't hate his parents as much as he hated Luke.
For a number of months there were minor skirmishes, Hux pursuing Luke's forces until they took refuge in Crait Castle, and the final siege began. His mother, his uncle, all that was left between Kylo and the throne, was inside. Victory was close.
Six months from when Kylo started his uprising, the doors opened and Luke alone stepped out. He wasn't in full armour but was armed and so Kylo stepped forward in similar attire. Luke looked gaunt and tired.
Kylo spoke first. "Did you come here to say you forgive me? To ask me to withdraw?"
"No." Luke seemed old and weary, but Kylo was all too aware of his reputation from his youth. Luke had trained Kylo when he was still a boy, until he developed the same worried look most people did when speaking to him. Even his own mother. It's like they had already judged him a bad ruler. He would show them. Luke just had to die.
Kylo drew his sword and Luke did likewise. As Kylo swung Luke dodged his blow with a nimbleness that was breathtaking given his age.
"You've played right into his hands, Ben."
"I don't answer to Ben anymore. After you killed her I left the old me behind."
Luke gave a wry grimace. "My point exactly. I didn't kill anyone. And I didn't ask anyone to on my behalf."
"I went there after the meeting. Her home was razed to the ground. You voted against her. As always you took away my choices. Who else would do make sure the choice was gone permanently?"
"I'm sorry I led you down this path, Ben—sorry, Kylo. It was Snoke. The one who is playing you like a fiddle."
Kylo scoffed. "I'm sure you are. Snoke voted for the marriage. Why would he kill her?"
Luke took a deep breathe. "Because he knew how you'd react? After the ball, the guards told me he left the palace and returned just in time for the meeting."
Kylo swung again. "You lie. You're trying to manipulate me.
"No, Ben. I'm telling you the truth. Who gains most when you take the throne? Who is going to become the second most powerful man in Alderaan?"
They clashed again. "And when I kill you I will be the most powerful person in Alderaan."
"Palpatine has an heir. A granddaughter. He's coming for Alderaan, Ben. You're going to need people who will be honest with you, tell you how it is."
"I'll outlive him the way I'm about to outlive you, too. I'll kill you, and her, all of it." Kylo put everything behind his swing, Luke seemingly not even trying to block it. Kylo skidded to a halt, feeling relief, worrying he had missed even though there was no way he could have.
Kylo turned around. Luke lay in the ground in a puddle of red, panting.
"Listen, because these are my dying words, and I don't want to waste my breath. If you believe me on one thing, it was Snoke. Snoke left the castle that night. He had time to get to Jakku and back. Poe was asking questions in Niima and Snoke was seen there. He always did dress rather flashy. Ask him. Why was he in a backwater like Jakku?" Luke was struggling hard. "I'll be with you always, Ben. Just like your father."
And then he was gone.
Someone in the distance shouted "The King is dead. Long live the king!" A round of long live the king resounded, but Kylo wasn't ready to celebrate yet. He led a company of men into the castle to find it was empty. His mother and the remainder of Luke's loyalists had used the distraction of the dual for the throne to escape.
As Kylo stood in the courtyard, pensive, Snoke walked up behind him, giving his congratulations and saying how he always knew Kylo would succeed.
Kylo even surprised himself as he turned without warning, swinging his already bloodied sword and cutting his mentor cleanly in half across his middle. Snoke's mouth opened in shock as he slid in two parts to the ground. There was an eerie silence amongst his previously jubilant army.
"I do not tolerate traitors. My mother has escaped. I want her found and brought to me alive."
