The Aleen mission was a humanitarian operation executed by Clone Commander Wolffe and the 104th Battalion.
Following a series of destructive groundquakes that shook the planet Aleen, the 104th Battalion and Clone Commander Wolffe were dispatched to provide aid. C-3PO and R2-D2 assisted by translating and setting up new equipment for the clone troopers. The two droids, while awaiting the system installations, investigated an open hatch and subsequently fell into the Aleen underworld due to another groundquake.
While navigating the tunnels, the two droids encountered three Kindalo who directed them to another inhabitant of the underworld, who revealed that the quakes were caused by toxic air entering through the unsealed hatch. After she departed, the droids were propelled back to the surface and sealed the hatch. Jedi Master Adi Gallia also arrived to assist with the mission, and the 104th met up with her after the operation was complete.