[2] When the World War I broke out, he was mobilised and initially he served in Daugavgrīvas fortress, later assisting in the formation of Latvian riflemen battalions.

Subsequently he travelled to Moscow, where he along with those who refused to join the Red Army, like his former commander Frīdrihs Briedis, took part in Savinkov's anti-Bolshevik organisation.

Initially he aided the formation of new units in Liepāja, and would later also serve at the front lines as a member of Kalpaks battalion.

[1] Before taking his life, Bolšteins left a suicide note directed to his superiors.

In his letter he wrote: To my superiors.We, the Latvians, built ourselves a brand new house — our country.Now an alien power wants to force us to tear it down ourselves.In this I cannot take part.