Ukrainian People's Army
Sosiura fought in Petliura's Ukrainian People's Army (the 3rd Haidamaka Regiment that was quartered in Bakhmut) during the winter of 1918 to the autumn of 1919, before being taken prisoner by Denikin's Volunteer Army. He was sentenced to death, but managed to escape. Later, after the UPR was overrun, he joined the Red Army.