From June 1916 to July 1917, Zagórski served as commander of the 3rd Infantry Regiment of the Polish Legions. The Oath Crisis took place during this time period, where Zagórski pledged his allegiance to the Central Powers, in contrast to the vast majority of his soldiers who did not. He imprisoned several of his soldiers and ordered for them not to be fed. When none of the prisoners complied with Zagórski's demand to pledge allegiance to the Central Powers, he ordered the soldiers to march shoe-less to an internment camp in Szczypiorno. Later, it was often recalled by the Polish Legions that as the column of shoe-less Poles marched past a furious Zagórski, the Polish soldiers bellowed out in unison the lyrics to "We Are the First Brigade", and added a fifth verse to the song where they verbally attacked Zagórski, ending the song with telling Zagórski to ""go f--- yourself"". As a result, Zagórski denounced several Polish Legion officers at the internment camp who entered undercover as regular soldiers with the aim of dividing the sentences among the imprisoned. Those denounced by Zagórski were transferred to another internment camp in Havelberg, where they were brutally treated, and even tortured.