German military history of 1871 to 1945 is often seen as a direct continuation of Prussian military history. Taking a closer look at the organizational and cultural background of German military forces produces a slightly more nuanced picture and makes it possible to divide the history of the German Army into five phases. Initially, the German Empire effectively had four different forces – the Prussian, Bavarian, Saxon, and Württemberg armies – united only in times of war. During the First World War, these German "armies" increasingly lost their prewar independence, while the war itself had a unifying effect on German society and on its armed forces. Following the defeat of 1918, the army of the newly founded Weimar Republic was developed as a small, elite force exclusively based on Prussian traditions. The 1936 rearmament then turned this force into a mass army, the Wehrmacht, which, while still sticking to Prussian traditions, struggled with various issues caused by rapid expansion. Finally, during the Second World War, the Wehrmacht evolved from a purely German force into one in which significant numbers of foreigners from all over Europe served as volunteers, resulting in an army transcending the boundaries of the nation-state.