The 1st Ustaša Regiment () was raised by Francetić and Ante Vokić in Sarajevo in September 1941. When the original commander of the regiment was killed, Francetić took over command, and the regiment grew quickly and gained a reputation for fanaticism and violence. Raised for service in eastern Bosnia, by December it had been dubbed the Black Legion () after adopting a black uniform. It was feared for its fanatical morale and fighting qualities, but also for the atrocities it committed against the Bosnian Serb population. It soon grew to a strength of between 1000–1500 men.