Born on the Free Rasalhague Republic world of Last Frontier, Cilla's life was shattered by the Clan Invasion, when she was forced to flee from the advance of Clan Ghost Bear against her homeworld. Her hatred of the invaders and the Bears in particular was only amplified by the loss of her brother Martin, a Fanjunkare in the 1st Freemen who died in the failed defense of Last Frontier.   
Cilla entered military training as soon as she was able to in order to seek revenge against the Ghost Bears. Cilla was one of the first cadets accepted into the newly opened Tyra Miraborg Memorial Academy in 3056. Entering active service with the 3rd Drakøns just in time to take part in Operation Bulldog, Cilla's actions during that conflict earned her recommendation for officer candidate training, which she graduated from in 3061 becoming a Löjtnant in the 1st Tyr.
When the Bears' response to the Word of Blake Jihad was to annex the seven remaining worlds of the Republic with the acquiescence of its government, Cilla was livid with rage. This betrayal was the start of her attempts to convince her comrades in the 1st Tyr to oppose the merger, but they fell on deaf ears as most were more or less in favor. Refusing to flee the Republic she loved, Cilla declined the offer of the departing Precentor to join the withdrawing Com Guards, and was ultimately discharged from the KungsArmé for refusing to participate in the Trials to remain a warrior on the Bear's touman.
Focusing instead on political agitation, Cilla became one of the most vocal resisters against the merger, penning endless volumes of anti-Ghost Bear propaganda and also directing much of her vitriol for those she saw as betraying the Republic, such as Christian Månsdottir. While mostly fighting the Bears on political terms, some evidence exists that Cilla had ties to numerous violent protests on former Rasalhague worlds and the KungsArmé mutiny in 3075. Going underground in the wake of the mutiny, with little chance of outside support and the continuing integration of Rasalhague and Bear governments, most assumed she would soon switch from advocating resistance to encouraging terrorism outright.
Following the terrorist bombing conducted by Motstånd on the 31st of December 3078 which struck at the Omni-Paradise Hotel on Alshain and killed 378 civilians - both Rasalhagian and Clan Ghost Bear in origin - as well as several members of the Unity Council and Christian Månsdottir, Cilla and the other leaders of Motstånd were pursued aggressively by the Ghost Bears.
As at the 9th of January 3079 Cilla was the last senior member of Motstånd known to still be alive, having narrowly escaped capture by Ghost Bear paramilitary police forces on the Ghost Bear Dominion world of Tinaca. Cilla remained alive and free for more than thirty years; she was involved in the resurgence of Motstånd in 3125 but was captured during a wave of assaults on Motstånd strongholds that same year. Captured on Vipaava by Galaxy Commander Dalia Bekker, who led Alpha Galaxy against the various Motstånd strongholds, she was finally brought to justice by the Rasalhague Dominion. Her capture also gave Dalia Bekker the popularity boost she needed to secure her own appointment to Khan of Clan Ghost Bear in 3126.
- Masters and Minions: The StarCorps Dossiers, p. 107 "Cilla Amdahl"
- Jihad: Final Reckoning, p. 60, "The Jihad in Review"
- Jihad: Final Reckoning, p. 11-12, "Terrorists Die In Firefight"
- Era Report: 3052, p. 50 "Factions - Clan Ghost Bear"
- Era Report: 3052, p. 52, "First Bear Guards (The Rage)"
- Invading Clans (sourcebook), pp. 21-22
- Era Report: 3145, p. 108, "Dalia Bekker"