Once during a mission, 1137 and their fellow clone trooper, 1139 were forgotten on a desert planet after their unit miscounted and departed. Ultimately, this proved fortuitous, for while abandoned the two soldiers learned of a CIS secret weapon project. As dutiful soldiers, 1137 and their companion resolved to destroy it. To aid in this endeavor, they built a TX-130 fighter tank, with which they destroyed the Separatist weapon. Soon thereafter, realizing their absence, a Republic gunship returned to retrieve the duo.
Having proven their competence, 1137, together with 1139, were then assigned to hunt the missing astromech droid R2-D2, their squad ordered by Supreme Chancellor Palpatine to find them before the Jedi. Travelling in a Nu-class attack shuttle, their first stop was the sector where R2-D2 was last seen, taking directions from a group of Rocket battle droids who were floating through space. Landing on an unidentified planet as their scanners picked up various droid signatures.. After struggling to find any droids, the clone squad was ambushed by various B1 and B2 battle droids, 1137's commander ordered their shuttle to give them cover fire while the other clones attacked the droids head on. The clone squad were able to quickly overwhelm them and steal the droid forces' Armored Assault Tank,only to be bombed from above by the clone forces in the shuttle, who had mistaken them for the enemy.
Knocked unconscious by the blast, 1137 dreamt of flying an Advanced TIE before being woken up by 1139. Going off to mope while their colleagues worked on rebuilding their arsenal,1137 was visited by Anakin Skywalker's Jedi Padawan Ahsoka Tano. Ahsoka began debriefing 1137 until the two were pursued by a Hyena-class bomber that shot at them until Ahsoka prepared to engage them with her Lightsaber, at which point three Rocket battle droids inside the bomber exited and surrendered. 1137 and Ahsoka speculated they were the same Rocket battle droids that directed 1137's squad down to the planet earlier, something which the droids denied. This line of questioning made 1137 briefly wonder how their squad was doing, only for them to disregard this line of thinking and chase the three droids away with Ahsoka. They were then contacted via Comlink by Palpatine, who commanded them to execute one of the contingency orders. 1137 cut Palpatine off, however, as he interpreted this order as Order 6, the order to throw away their comlink as quickly as possible. 1137 then regrouped with 1139 as Ahsoka departed.
Their partnership with 1139 became momentarily contentious, however, when the latter expressed desire for names to supersede their numerical designation—a sentiment not shared by 1137. Nevertheless, their disagreement was quickly resolved, and their search continued. Eventually, it took them and their pilot to an ice planet, whereat their ship crashed. As with their previous abandonment, this, too, proved fortuitous, as it begat a chance encounter with none other than the prominent CIS leader, Nute Gunray. Deciding against direct assault upon the Neimoidian's shuttle, 1137 and their companions settled on a ruse. Feigning that they were selling Clone Scout cookies, 1137 and the pilot distracted Gunray while 1139 and their commander subdued him. This being accomplished, the clone troopers absconded with the shuttle.
The next stop on the astromech-hunt was Endor. Mistaking the local flora as being indicative of hostile Wookiees, 1137 retreated into the shuttle. This action drew the attention of a local Ewok, who sought to establish contact with 1139. However, the Ewok's attempt ultimately resulted in the capture of the whole party. Taken to the natives' camp, 1137 found themselves with their comrades-in-arms being employed as percussion instruments and 1139 being roasted. Their dilemma proved temporary as soon Nute Gunray arrived, escorted by droids and tanks, seeking vengeance for his humiliation. This intervention inadvertently allowed the troopers to free themselves, after which they quickly dispatched their foes. Dismayed by their ferocity, Gunray retook his shuttle and fled.
Despite the rather chaotic turn of events, 1137 and their companions retained enough composure to search for another means of transportation, which ultimately proved to be three BTL-B Y-wing starfighters. Leaving Endor, they were intercepted by a Venator-class Star Destroyer. Aboard was, to 1137's surprise, none other than Supreme Chancellor Palpatine. Extremely displeased with their performance, citing the fact that Anakin and Ahsoka had already recovered the missing R2-D2, the Republic leader discharged them from the Grand Army of the Republic. Without further ado, 1137 and their comrades took a beach-side vacation.
1137 and 1139 are the numbers before and after 1138. The name of the comic that in which 1137 and 1139 are introduced, "Always count your clones before take-off," derives from the plot point of the duo having been left behind.