Cancl Rosan was a soldier of the Galactic Empire known as a stormtrooper. He spent the majority of the Galactic Civil War fighting under the command of General Brenn Tantor.
After his commanding officer, the general, was incarcerated on Kalaan for disobeying an order that involved the killing of civilians, another stormtrooper, Gana Lant, persuaded Rosan, along with eight other stormtroopers who had served under Tantor, to choose loyalty to the man who had led them through numerous battles over the Galactic Empire which had betrayed him.
In a move that would prove disastrous, Grand General Malcor Brashin tasked them with guarding Tantor while he was held in an open-air cell. Lant freed Tantor and told him about the squad's allegiance. With Tantor now free, the stormtroopers commandeered the TR-MB prototype and launched an assault on the prison, liberating Luke Skywalker. The group then journeyed through the canyons of Kalaan, gathering support from the Kalaanite resistance until they reached a Rebel base established by Tyr Taskeen. From that location, they were transported to Taskeen's fleet, where it's presumed they were temporarily detained along with their general. Upon their release, they most likely resumed their service to the Rebellion as infantry under the leadership of Tantor.