As a Hells Angels support club, Cannonball was aligned with the HA prospect chapter Overkill MC against the Undertakers MC, a prospect club of the Bandidos, during the Nordic Biker War in the 1990s. The Cannonball vice-president was shot and wounded by an Undertakers member at a restaurant in Helsinki on 1 April 1995. Two Undertakers bikers, including club president Marko Hirsma, were assaulted by members of Cannonball and Overkill on 27 September 1995 outside a courthouse in Pasila, Helsinki when they arrived to attend the court case of two other Undertakers who were on trial for attacking Overkill's clubhouse with a rocket-propelled grenade. In 1996, Overkill and the Undertakers patched over to the Hells Angels and Bandidos, respectively, while Cannonball became independent. The biker war formally concluded with a ceasefire on 25 September 1997. Since the end of the conflict, the clubs have operated in parallel rather than competing with each other.