The Battle of Korriban was a key battle during the Sith Crusade. It was a major morale booster to the Sith forces to conquer the ancient homeworld of the Sith Order but it was not without heavy losses. Over half the Sith force perished in the attack and it was also the first time the Sith had encountered Jedi during the war.
Although publicly the reasons for the invasion of Korriban was to reclaim the ancient Sith homeworld, and it did provide a huge morale booster for the Sith forces. The true reason was much deeper.
By the year 64 ABY Korriban had become the new capital of the Decreton Empire, and by the time of Darth Abeonis' death, it had become a green and lush world; this had been thanks to Darth Abeonis' Mass Terraforming Program.