A prominent general and servant of the Old Republic, Leia Lydendara fought as a young soldier in the Clone Wars, and won several battles in her prime against both Jedi and Mandalorian opponents, most prominently during the Battle of Mandalore itself, fighting in hostile conditions on the harsh jungle world.

Lydendara was also the proponent of a new form of battle, the Mass Assault Doctrine, which left only minimal forces to defend planets behind the main lines, in order to deliver incredible firepower where it was needed most, whether from orbit or during ground assault, often upon single planetary targets. It was this strategy which won the day when the Republic's forces were suffering terrible losses in the Siege of Corulag. She was, along with Grand Admiral Galen Veich, one of the two most prominent figures of the last days of the Old Republic. She was one of only fourteen military leaders to achieve the rank of Master Grand Marshal across the thousand generations of the Old Republic. She was also the chief engineer of the Republic's military efforts during the “intrabellum” phase of the Mandalorian Wars, which threatened to distract the Republic’s efforts during the Clone Wars.

Though she generally distrusted and felt a strong distaste for politicians, Lydendara became a confidante and ally of Senator Palpatine during his rise to prominence in the Galactic Senate, and supported his move to establish governor-centric mode of legal control which would later become a central pillar of the Galactic Empire. Unlike many other politicians, she felt Palpatine embodied the unity and security she genuinely believed was an essential component of civil society, where many other politicians seemed more intent on arguing only for their own interests.

For a time, before the Second Clone War, she was vocal in the Galactic Senate, appearing before various committees, as well as making several public appearances in support of various initiatives. In particular, it was a series of passionate speeches in support of the statute to replace the Jedi Order with civilian judiciary appointments, which contributed most to the legal shift in galactic politics at the time. Many scholars now believe Palpatine may not have been as successful as he was reigning in the extensive powers of the Jedi had he not enjoyed Lydendara’s vocal support.

After her retirement, Palpatine sought to resurrect her image for political ends—which cynics pointed to as a belated effort to counter the rising influence of Galen Veich—but Lydendara was insulted by the manner in which Palpatine subsequently manipulated her few public appearances. She had a falling out with him shortly before he became Emperor, by which time he had become little more than a figurehead. Lydendara later frequently referred to Palpatine as a powerless puppet of the Moffs and Grand Admirals of the Imperial war machine she herself knew all too well. The inspired politician she had known and respected in her youth was long gone.

As the New Order began to oppress and restrict the people of the galaxy, Lydendara became horrified at what she had participated in and retired from public view to a remote world on the Outer Rim. While she essentially distanced herself from Palpatine and the Empire in general, her likeness remains a frequent image on Imperial propaganda thanks largely to her legend and enduring popularity amongst Imperial citizens.