 Since his teens, Ulrych was an active member of Polish independence organizations, such as the Riflemen's Association.After the outbreak of World War One, he joined Polish Legions of Józef Piłsudski, becoming one of the officers of the 1st Legions Infantry Regiment.In late stages of the war, he was transferred to his native Kalisz, where, as a member of the Polish Military Organization, he commanded the disarming of German soldiers (November 1918).