100‑year‑long history of psychiatric treatment in the Polish Army can be divided into several periods. The first one (1918–1939) when, almost from scratch, an efficiently functioning military psychiatric service was created. The second one (1940–1945) was the years of German occupation and the establishment of the Polish Armed Forces in France and then in Great Britain, where the Polish Faculty of Medicine at the University of Edinburgh played an important role in educating future military physicians. The third period (1946–1963), in which psychiatric protection of soldiers was provided by civil psychiatrists. The fourth period (1964–1989) is characterized by dynamic institutional, personnel, scientific and didactic development of military psychiatry. We owe this to professor Rydzyński, the creator of post‑war psychiatric military treatment. The fifth period (1990–2002) is related to socio‑political changes in Poland and a need to restructure and reduce the armed forces, as well as a closure of the Military University of Medicine (2002). The sixth period (2003–2018) is associated with creation of the Military Medical Department at the Medical University of Lodz, formed from the merger of the Medical University of Lodz and Military University of Medicine (2002). This allowed to educate cadets, the Ministry of Defense scholarship holders, to become military physicians.