He was born May 9, 1895, in Lejasciems, Gulbene Municipality of Latvia as the son of a Latvian father and an Estonian mother.

During the First World War, in 1916, Eidemanis was drafted into the army of the Russian Empire and sent to the Kiev military school, after which he was appointed a junior officer of the Siberian Rifle Regiment.

He was one of the organizers of the Bolshevik coup in Siberia, after which he worked in the Council of Workers' Soldiers' Deputies of Kansk.

The army under his command played a decisive role in the defense of the key to Crimea, the Kakhovka bridgeheads.

Beginning in 1925, he published several prose works and was active in the Latvian culture and education society "Prometeys".

He was shot on June 12 in Moscow, together with Tukhachevsky, Iona Yakir, Ieronim Uborevich and other military figures.