Because Germany wanted revenge and everyone felt the same in a way. They felt like Hitler could guide them in the right direction so they all came together and listened.
Well Germany got mad that everything was blamed on them.Germany had to pay alot of money for the damage. They started doing this process called appeasement where they were starting to let Hitler break some rules on the treaty.They finally wanted to stop him when he invaded Poland in 1939.And yes I think nationalism was a big factor into starting WW2 because Germany started to have Nazis which were a big part.i hope this helps! ☺️
