Ka kammala wannan jumla: Kubiliūnas ya sauke karatu daga Realgymnasium a Riga kuma ya ci gaba da karatunsa a Makarantar Sojoji ta Vilnius, inda ya sauke karatu a watan Disamba na shekara ta 1914. A lokacin Yaƙin Duniya na I, ya yi aiki a rundunar sojojin Rasha a Gabashin Gabas. An sanya shi zuwa 2nd Riga Battalion na Latvian Riflemen. An ba shi lambar yabo ta Rasha da yawa, gami da Gicciye na St. George da haɓakawa zuwa kyaftin don ayyukansa a lokacin
Yaƙe-yaƙe na Kirsimeti a 1916.