From 1910 to 1917, he lived with his parents in Łomża, Poland, where his uncle A. Daukša owned a large dairy farm.

In 1917, Žemaitis returned to Lithuania and settled down in the village of Kiaulininkai, near Šiluva, where his grandparents lived.

After his studies, Žemaitis was promoted to captain and commanded artillery units of the Lithuania military forces.

At the beginning of the war between the Soviet Union and Nazi Germany, Žemaitis was at the proving ground of Varėna.

After receiving the order to retreat to the east, Žemaitis and a group of soldiers consciously fell behind and surrendered to the Germans.

Posthumously Jonas Žemaitis-Vytautas was awarded the rank of brigadier general and was officially named as the fourth President of Lithuania in March 2009.