After the collapse of this organisation Bolšteins returned to Latvia on December 28, 1918. There he joined Latvian army. 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. On July 12, 1919 Bolšteins obtained the rank of lieutenant colonel. On August 9 he was appointed the commander of the 9th Rēzeknes Infantry Regiment. After the liberation of Rīga he was made a colonel. For the remnant of the Latvian War of Independence he served on the Latgale front.