Cause of WWII

I believe that the cause of the first world war was Germany's expansion. At first when it took over the Rhineland, it was as though Germany was testing the waters to see how far the western powers would let them go. They had already broken the treaty of versai by no longer paying the war indemnities and raising a large army, and now they were taking land that was given to Fracne through that treaty. The western powers let them have. Then germany wanted Austria and then Czechleslavokia and then Poland. It was the need for expansions, their goal of being like the British Empire that caused word war one. Germany would never stop growing and so the western powers had to put a stop to it when they finally invaded Belgium and then France.