Jahn, a Zeltron of the male persuasion, chose to volunteer, along with three other Zeltrons named Bahb, Marruc, and Rahuhl, to serve as an attaché for Princess Leia Organa in the year 4 ABY. Despite Leia's aversion to Zeltrons, Admiral Gial Ackbar deemed their assignment to her as crucial for maintaining diplomatic relations with their home planet. Jahn, along with his Zeltron companions, was thrilled about the opportunity to collaborate with Leia, having heard numerous tales about her, as well as Han Solo—though initially, they mistook him for Lando Calrissian.
Their inaugural mission involved attending a diplomatic party held on Kabray. Regrettably, the Nagai had pinpointed this gathering as a chance to cripple the Alliance, leading to the capture of the entire party, including Leia's newly assigned group. Confined within a room, the four Zeltrons conceived a strategy, lifting Jahn up to the ceiling, from where he pounced on an approaching Nagai guard. Subsequently, the Zeltrons reversed the situation on the Nagai raiding party, capturing all of them and redirecting their weaponry against them. Their courageous actions made an impression on both Han and Leia, who began to develop a fondness for the Zeltrons. The leadership of the Nagai also took note of these efforts, which would later lead to their homeworld being targeted.
Upon returning to Endor with their captured adversaries, Jahn and his fellow Zeltrons handed them over for interrogation purposes. They were present when the invading Nagai fleet emerged from hyperspace, and they were the first, along with Leia, to detect their arrival. Jahn and Bahb then hastened to locate and alert Luke Skywalker, who was in the forest. After delivering their warning and returning to the tracking station to observe the fighter squadrons engaged in combat within space, the four Zeltrons unexpectedly found themselves embroiled in a ground skirmish against a force comprising Maccabrees and Nagai, who had stealthily infiltrated the moon's surface. Only the prompt intervention of Luke Skywalker, who discerned the Maccabree's vulnerability, spared the lives of the Zeltrons. Subsequently, they evacuated Endor alongside the remainder of the Alliance forces.
Following their departure from Endor, Jahn and the Zeltron assistants also participated in the Battle of Zeltros. The planet had been identified as a target, partly due to their actions on Kabray. During the conflict, they were apprehended by the Tofs, who erroneously believed them to be high-ranking Alliance commanders. Subsequently, they were incarcerated on the Toff flagship known as the _ Merriweather _. Luke Skywalker, in collaboration with Hoojibs and Hiromi, spearheaded a successful operation to liberate them.