Well that'd mainly be the Treaty of Versailles after Germany's defeat in WW1, with extremely unfair terms for Germany, giving them the blame and absurd reparations for the damage caused [Which might i add, was started by Austria-Hungary] So since Germany couldn't pay, they printed money, hyperinflation, and than unemployment skyrocketed and Hitler seized power due to the people's displeasure with the new situation. Japan however, after the Meiji restoration rapidly industrialized and modernized to this new world, and attempted to start an eastern empire after invading Manchuria and after the Russo-Japanese war they had a burst of nationalism, and after WW1 seizing Germany's eastern colonies. They later invaded china [Which is debateably the real start to ww2]. All this gave them more territory and thus, power.
