Mission to Dromund Kaas

In 3960 BBY, the Jedi Knights Revan and Malak followed the trail of the Sith Emperor from Nathema to Dromund Kaas, the capital of the True Sith Empire, and embarked on a months-long mission in order to assassinate the Emperor. Posing as mercenaries, the two Jedi were able to gain the confidence of the Imperial Guard Yarri, but the Guardsman deceived them and led the two into a trap where the Emperor dominated their wills. Turned to the dark side of the Force and anointed as Darth Revan and Darth Malak, the two new Dark Lords of the Sith were ordered to seek out the Star Forge and to wage war upon the Galactic Republic, though they broke free of the Emperor's control not long afterwards and decided to seek out the Star Forge for themselves.