3,962 BBY

Disagreeing with the Jedi Council's decision not to act in the Mandalorian Wars, Jedi Knights Revan and Malak join the war effort and command a Republic fleet against the Mandalorians. A number of Jedi follow them.
Knights of the Old Republic video game.
 
 
 

3,960 BBY

Under the leadership of Revan and Malak, the Republic defeats the Mandalorians, who surrender unconditionally. Revan and Malak then take their fleet into deep space to supposedly stop a number of remaining rogue Mandalorians. They are not heard from for months, during which they completely turn to the dark side of the Force and use the ancient Star Forge to create a fleet of warships.
Knights of the Old Republic video game.
 
 
Lost Tribe of the Sith: Purgatory
(eBook - Del Rey Books - Oct 2010)
 
Lost Tribe of the Sith: Sentinel
(eBook - Del Rey Books - Feb 2011)
 
 
 

3,959 BBY

The War of the Star Forge begins. Revan and Malak's fleet returns to Republic space, along with another fleet of mysterious ships. Revan and Malak declare themselves Sith Lord and apprentice. They begin attacking Republic planets still weakened by the previous war. Many of their original Republic officers and troops remain allied with them, including one of the war's heroes, Admiral Saul Karath. The Jedi join the Republic war effort.
Knights of the Old Republic video game.
 
 
 

3,957 BBY

Following a battle with Republic forces, Darth Revan is nearly killed by a group of Jedi led by a young Jedi woman named Bastila Shan. Bastila's skill in the rare art of battle meditation is credited with helping win the battle. In the wake of Revan's apparent death, Malak steps in as the new Sith Lord and the war against the Republic continues.

Hoping to use Revan's power to eventually defeat the Sith, the Jedi take away the Dark Lord's memories and even implant false ones. Revan is placed onboard Bastila's ship, and will eventually awake with apparent amnesia.

Knights of the Old Republic video game.
 
 
Knights of the Old Republic: Opportunities
(Parts 1-3 - Miniatures game scenario - Wizards.com - Oct-Nov 2006)
Shortly after Malak takes control of the Sith.