Kammala jumla mai zuwa: A shekara ta 1914, ya shiga rukunin bindigogi na Sojojin Poland, kuma ya ba da gidansa a Zembrzyce don warkar da sojojin da suka ji rauni. A wannan lokacin ne ya ɗauki "Zyndram" (ravens) a matsayin sunansa na biyu. Da farko ya yi yaƙi a ƙarƙashin jagorancin Kyaftin Zbigniew Dunin-Wasowicz, sannan ya yi aiki a hedkwatar ma'aikata na Polish Legion. A cikin 1915, an canza shi zuwa umurnin Lieutenant-Colonel, Edward Rydz-Śmigły; shiga cikin yaƙe-yaƙe na
Jastków, Kostiuchnówka, da kuma wasu da yawa. A shekara ta 1916, ya kamu da cutar typhus. Kodayake ya warke, wannan ya kawo ƙarshen sa hannu a cikin yaƙin don haka, a cikin 1917, ya koma Kraków kuma ya shiga cikin shirya gidan kayan gargajiya na soja. An ba shi mukamin kyaftin a 1918, ya yi aiki a sashen farfaganda na 2nd Rifle Division, kuma ya ba da lacca a Cibiyar Nazarin Gidauniyar Soja. Ya yi aiki har zuwa 1922, lokacin da aka canja shi zuwa ajiyar.