Alantas was the eldest of four children of a family of Lithuanian farmers in Sidabravas. Alantas' father briefly worked in the United States and managed to purchase of land from a former manor in near Radviliškis. His brother became a theater director. Alantas was taught by a "daraktorius", a travelling Lithuanian teacher educating pupils in secret during the Lithuanian press ban. In 1912–1923, Alantas studied at the Šiauliai Gymnasium, with a half-year break in 1919 when he volunteered for the Lithuanian Army to fight the West Russian Volunteer Army in the Lithuanian Wars of Independence, despite being only 17 years old. From sixth grade onward, Alantas became immersed in literature, writing poetry and participating in the activities of the Ateitis Catholic Youth organization. Like many Lithuanian writers, he published his literature under a pseudonym, choosing "Alantas", a tributary of the river Minija.