The end of WW1 resulted in Germany and other few countries losing and having to sign harsh treaties.”The Treaty of Versailles” was directed at Germany, having to reduce military, not have an Air Force, pay an enormous sum of money they couldn’t pay.In order to get the money Germany started printing money a lot, but when you do that it only makes the value of each money be less and less valued.Then there was Hitler, having fought in the 1st world war people loved him and he quickly rose to power.He needed someone to blame for all of Germanys problems, and he decided to blame the Jews.
He wanted to have a world with only people of the Ayran race.But to do that he needed living space(aka taking over the world) but a good portion of Europe would do for now.
There was another country,Italy.Italy had been on the winners side in world war 1,still super proud of their win they didn’t move on.They still dispatched messages via bikes not telegraphs and drills were pretty vague.Italy hade hoped to gain much more territory after WW1 but they instead only got a small amount of what they really wanted.On top of that and a weak government meant Italy was in ruins , so when a Mussolini came along and said he could change everything.The people loved him.
Mussolini and Hitler had a lot of similarities:Both wanting to expand to gain more territory.
This is all I Know ,hope this helps for whatever you are doing!