The sinking of the Lustania? I think that was the name of the cruise ship, and was a rallying cry for the US into ww1, as Americans died in the transit.
To prevent spread of communism after the end of WWll
Germany had to join the league of nations.
Germany had to pay reparations, and in an attempt to pay them off, they mass produced money which lead to inflation and the German money becoming practically worthless.
Germany’s military was majorly downsized in order to prevent another war of arms from them.
Germany’s territories were given to other countries, causing its own territory to become smaller. This is a main reason for why the Germans were angered into causing WWII.
Hope this helps!
