The citizens of Austria-Hungary (roughly 3,000) were then forcibly drafted into the Austro-Hungarian Army or the Polnische Wehrmacht, demoted to privates and sent to Italian Front, while people born in other parts of occupied Poland were interned in prisoner of war camps in Szczypiorno and Beniaminów.
Approximately 15,000 of them were confined in internment camps in Beniaminów and Szczypiorno, while almost 3,000 were drafted to the Austro-Hungarian Army.
In February 1918, he was released from the internment camp in Beniaminów and joined the Polnische Wehrmacht.
Following the Oath Crisis of 1917 and Legions' switching sides, Biernacki was interned in Beniaminów together with a large group of former soldiers of the Legions.
Wounded in the battle of Łowczówek, after the Oath Crisis of 1917 he was arrested and interned in the POW camp in Beniaminów.