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 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, whereupon only minimal forces were left to defend planets behind the main lines, and incredible firepower was brought to bear, from orbit and during ground assault, 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 Veich, one of the two most prominent military leaders of the Old Republic. She was also the chief engineer of the Republic's war efforts during the Mandalorian 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 power, and supported his move to establish 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, whether personal or planetary. After her retirement, Palpatine sought to resurrect her for political ends, much as Veich had done decades earlier, but Lydendara was insulted by this offer and had a falling out with the Emperor, who she already suspected was a mere figurehead, a powerless puppet of the Moffs and Grand Admirals of the Imperial war machine.

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.