During the eras of the Great Galactic War and the Cold War, the Human male who held the title of Mandalore the Lesser served as the leader for the Mandalorian warrior clans. Prior to his ascension to Mandalore, he existed as a youthful member within the then-disunited warrior clans. As one of numerous Mandalorian gladiators, he resided on Geonosis, engaging in arena combat to gain prestige. While a capable fighter in his own right, his sudden rise to prominence was largely due to the influence of Imperial Intelligence, the espionage division of the reconstituted Sith Empire.
Agents of Imperial Intelligence saw in this young gladiator a potential instrument to unify the Mandalorian clans and guide them into an alliance with the Sith. To rapidly elevate his status, they manipulated his gladiatorial contests and spread rumors of his impending coronation as Mandalore, the warrior-king of his people. He embraced the title and its associated power, but in doing so, became beholden to the Empire that had propelled him to this position. As a demonstration of his allegiance, the newly appointed Mandalore commanded his followers to establish a blockade along the Hydian Way. This act severely weakened the Galactic Republic, the Empire's adversary, and seemingly secured a Sith victory in the Great Galactic War.
Despite the Hydian Way blockade's year-long duration, it was eventually breached by daring smugglers under the leadership of the Mirialan Hylo Visz. Following this conflict, Mandalore sought to revitalize his warriors by initiating the Great Hunt—a galaxy-wide competition with the promise of glory. However, the victor of this competition challenged Mandalore to a duel, ultimately defeating and killing him, thus claiming the title of Mandalore the Vindicated. The galaxy would later learn that the Mandalore who had risen to power on Geonosis was merely a puppet of the Empire, leading to his historical designation as "the lesser" among the Mandalores.
During the Great Galactic War, the reconstituted Sith Empire sought the Mandalorians' military support, but only a small fraction agreed to fight alongside them. To secure the allegiance of all Mandalorians, Imperial Intelligence resolved to install a new Mandalore who could unite the dispersed clans.
The man who would become this Mandalore began as a gladiator in the Geonosis arenas. Beyond his natural combat abilities, Imperial Intelligence ensured his victories by sabotaging his opponents. Achieving considerable fame, he claimed the title of Mandalore and summoned the scattered Mandalorians to reunite. They responded, and he pledged to lead them to greatness. However, this new Mandalore was secretly a puppet of the Sith.
The alliance between the Sith and the Mandalore quickly broke the war's stalemate when he directed the Mandalorians to blockade the Hydian Way.
This blockade made the Hydian Way inaccessible, significantly hindering the Republic's war efforts and triggering a severe economic crisis in the Core Worlds. Knights of the Jedi Order, fighting for the Republic, attempted to break the blockade but were decisively defeated by the Mandalorians. Seeing an opportunity for profit by defeating the Mandalorians, the Mirialan smuggler Hylo Visz later led a group of smugglers against the blockade, resulting in the Mandalore's warriors' defeat and the reopening of the Hydian Way.
After the signing of the Treaty of Coruscant, Mandalore the Lesser tried to revitalize the Mandalorians and regain their support by reviving the ancient, galaxy-spanning Great Hunt. However, the victor of this revived Great Hunt challenged Mandalore the Lesser to a duel, fatally shooting him, and then declared himself the new Mandalore.