In January 1915, the entire XX Army corps was destroyed in the Augustów forest's and Zemitāns was taken Prisoner of War in February 1915.

After German coup on 16 April 1919 he was first Latvian senior officer who proclaimed that he maintains full loyalty to Ulmanis provisional government.

He led the brigade in the fight for liberation in Northern Vidzeme during the Battle of Wenden, an operation conducted by General Ernst Põdder of the 3rd Estonian Division.

When attack of the Bermontians started Zemitāns was commanding officer of the all Latvian units in Riga front.

He failed to organise the defence of Riga and left bank of the Daugava and was dismissed from duty and replaced by Mārtiņš Peniķis.