Graphic Novel
Published as Tales of the Jedi:
The Fall of the Sith Empire.

This story is collected in:

Tales of the Jedi: Volume 1

Comic Book series
Published June thru October 1997 as Tales of the Jedi: Fall of the Sith Empire #1, 2, 3, 4 & 5 by Dark Horse Comics:

Issue #1Issue #2

Issue #3Issue #4

Issue #5

Synopsis:
THE GREAT HYPERSPACE WAR
The Sith Empire has rallied its forces for an all-out battle for control of the galaxy. Their goal: Crush the Republic. And with so many Sith masters amongst them, the goal is not unachievable. As Naga Sadow readies his fleet to attack, one lone person threatens to undermine the entire campaign, Jori Daragon. She isn't a Jedi. She doesn't come from a military background or have a history of fighting. She's an explorer, a mapper of hyperspace who stumbled on the plans of the Sith. And she just may be the savior of the Republic.
Jori Daragon is on trial for offenses against Empress Teta's government. But far from being a lawbreaker, Jori is trying to reach the Empress, to warn her of the dark plans of the Sith Empire. If she is found guilty, she will be confined to a colony planet. And then nothing will stand between the Empress and the Sith.
Before the Empire held sway over the galaxy... before the Rebel forces rose up to create the New Republic... there was the time of the Old Republic. The story of how that grand oligarchy fell from power begins here, in an episode titled "First Encounter".
The Sith invasion rages on, as the dark side of the Force takes the upper hand over the Old Republic. But Dark Lord Naga Sadow is about to learn that winning a battle is not the same as winning a war!
Featuring the historic confrontation between the Old Republic and the Empire, The Fall of the Sith Empire cannot end but with the victory of the Old Republic. But even winners have losses, and the Sith Empire walks away from this battle with a victory of its own... one which will later spell doom for the Old Republic.

Synopsis taken from Dark Horse Comics, www.darkhorse.com.