Żytkowicz was an officer in the Polish Army active in the defense of Poland against the Nazi German invasion of September 1939, and retreated with the army across the border to neighboring Romania after the Soviet Union also invaded Poland on 17 September as an ally of Germany. He made his way to French-administered Syria, where the Polish forces regrouped as the Independent Carpathian Brigade, later crossing into British-administered Palestine when France capitulated to Germany. He saw action at Tobruk, Libya, and served in the Italian campaign against Germany as part of the Polish Second Corps under General Władysław Anders.