World War One specifically but the late 19th Century to the early 20th century more broadly. I'm not German but from 1871 when Germany became one country to either the end of Weimar Germany in 1933 or the beginning of the Second World War in 1939 are good markers of the period I mean.

There is just a lot going on in terms of colonialism, technological growth, ideologies, the international politics before WWI and the consequences of the war. A lot of class based stuff as well. In the UK there was all kinds of reform going on, the Labour party becoming important and other countries catching up with the British Empire economically.