While there wasn't a single overarching belief, many Germans of the bourgeoisie and the intelligentsia (including the German leadership) in 1914 felt:
- a growing feeling of encirclement stemming from the changing diplomatic landscape. Possibly since the end of Bismarck but definitely since the formation of the Entente in 1907 with Russia, France and England forming stronger and stronger anti-German ties.
- that the other great powers (unjustly) denied Germany her place in the sun ("Platz in der Sonne"), especially in regards to colonies. This was coupled with the feeling of an exceptionalism due to, among others, Germany's quick economic and military successes (especially and including the War of 1870) since unification and its cultural and scientific output. Ultimately, this feeling also influenced the overarching war goals of creating a German hegemony in central Europe and the acquisition of further colonies and territories from the losers of the war.
- that there was a growing lifestyle decadence and unmanliness, especially in other Great Powers but also in Germany, that could be cleansed with steel. For many, at the same time, war was an escapism from daily life. And sacrifice in the name of the state was considered a patriotic duty.
- that they could win the war, even if it required sacrifice as there were many victories but few losses in recent memory (e.g. War against Denmark, War against Austria, War of Unification, the Boxer Rebellion, the Herero Rebellion). At the same time, many also thought that the odds were increasingly turning against Germany, so the sooner the war starts, the better the odds for Germany.
This support expressed itself in patriotic marches in the cities, the "Geist von 1914" (Spirit of 1914 or "Augusterlebnis"). Proponents for a patriotic war also included notable intellectuals like Max Weber or Thomas Mann.
Anti-War sentiments and demonstrations were less common and more commonly carried by the countryside and the workers, though the Social Democrats (SPD), in the end, supported the war.
With the war unfolding, many of these ideas faded and the war gathered its own momentum. Former patriots became disillusioned as the reality of war set in, with a death toll in the millions.
Following the war, many others considered the war and the Treaty of Versailles a humiliation. This was instrumentalized in e.g. the Dolchstoßlegende (stab-in-the-back-myth, i.e. the myth that Germany was undefeated in the field, but stabbed in the back by politicians or the Jewish population).