In 3 BBY, while searching for a suitable location for the rebellion's base construction, Kanan Jarrus and Ezra Bridger, both Jedi, engaged in a duel using their lightsabers against the Inquisitors known as the Seventh Sister and Fifth Brother. This confrontation occurred on the planet of Oosalon. Ultimately, the Jedi managed to escape the encounter.
After the Imperial attack on Garel, the Phoenix Cell, aided by the Spectres, sought a secluded world for a permanent rebel headquarters. Among these rebels were Kanan Jarrus, a survivor of the Great Jedi Purge, and his apprentice, Ezra Bridger. As members of the Jedi Order, they were relentlessly pursued by the Galactic Empire's Inquisitors. The Fifth Brother and [Seventh Sister](/article/seventh_sister], two such Inquisitors, hunted Kanan and Ezra for several months, hindering the rebellion's base-seeking efforts.
On the stormy planet Oosalon in 3 BBY, Kanan, Ezra, and the astromech droid Chopper arrived. Their mission was to scout the planet as a potential site for a rebel base. While exploring the Oosalon Mesa, Kanan and Ezra were ambushed by the Fifth Brother and Seventh Sister, leading to a lightsaber duel between the two pairs. The Jedi attempted to contact Chopper, who was piloting the auxiliary ship Phantom, but received no response. During the battle, the Jedi successfully destroyed one of the Seventh Sister's ID9 seeker droids. As the fight continued, the Fifth Brother employed the Force to push Ezra off a cliff. However, Kanan used his abilities to levitate his apprentice to safety and grab his hand.
Continuing their engagement with the Inquisitors, Ezra utilized the Force to summon a large tibidee. The master and apprentice then jumped off the cliff, escaping on the back of the tibidee, which carried them to safety. Once they were airborne, Chopper picked them up in the Phantom. The rebels then departed into space aboard the Phantom. While in hyperspace, Kanan coordinated with Hera Syndulla and the rest of the Ghost crew to rendezvous in deep space to safeguard Phoenix Cell from Imperial agents.
After rejoining their team on the Ghost, Kanan confided in Hera, expressing his concern that the Inquisitors were hindering his and Ezra's ability to aid the rebellion in establishing a base, fearing they might have to separate from the rebellion. Later, the two Jedi met with Ahsoka Tano, a former Jedi Padawan, who advised them to seek guidance from Master Yoda at the Jedi Temple on Lothal. Leaving the other rebels, the Jedi, Ahsoka, and Chopper traveled to Lothal on the Phantom. While Chopper waited outside, the Jedi and Ahsoka entered the temple.
Inside, Kanan underwent his Jedi Trials and achieved the rank of Jedi Knight. Meanwhile, Ezra encountered Yoda, who cautioned the young Jedi against fighting, warning of potential destruction. As Ezra was committed to supporting the rebellion, Yoda advised Ezra and his companions to locate the planet Malachor. Simultaneously, Ahsoka experienced a Force vision of her former mentor Anakin Skywalker and discovered that he had indeed become Darth Vader. The three managed to escape with Chopper just before the Seventh Sister and the Fifth Brother infiltrated the temple. After assisting the rebellion in establishing Chopper Base, the two Jedi, Chopper, and Ahsoka set off on their journey to Malachor.
The Duel on Oosalon served as the introductory sequence for the Star Wars Rebels episode "Shroud of Darkness," which originally aired on March 2, 2016.