The author reconstructs the biography of the Polish doctor, Dr Stefan Szuman (1889–1972), later a professor at Jagiellonian University (1928–1961) during his period in the German army (1914–1919). S. Szuman, who acquired the state right to perform the profession of doctor in the German Reich on 7 September 1914, as well as the level of medical doctor on 23 December 1914 at the Faculty of Medicine in the Ludwik Maximilian University of Munich, formally served in the German army in the years 1914–1919. He served as a military doctor on the eastern front in the fight against Russia (from January 1915 until April 1916), firstly in Mazovia and Kujawy, then in Volhynia. Later he served on the western front – from April 1916 until December 1917, on the border between France and Belgium. During the night of 30 November and 1 December 1917 he was heavily wounded in the leg during the Battle of Cambrai in the Nord-Pas-de- Calais region near Raillencourt-Sainte-Olle, next to Cambrai and Bouchain. For his service in the German army, he was awarded the Iron Cross 2nd class medal (at the turn of 1917/1918). After his recovery in Aachen and Torun, he was transferred to serve in the military hospital in the citadel in Hannover (from May until December 1918). After 9 December 1918, he returned to Torun, where he stayed until 17 May 1919, working as a garrison doctor in the clinic of his father – Dr Leon Szuman, still formally an officer in the German army until 19 March 1919 as a citizen of Germany. On 20 May 1919, he was accepted into the Polish Army at the rank of captain in Torun, which was still inside the German partition. On 31 May 1919, S. Szuman illegally crossed the Polish-German border near Torun and succeeded in reaching Wielkopolska.