There were many immediate causes for the two World Wars, but also there were many other causes that contributed to this. Some of these causes were mentioned below:
i) The immediate provocation for World War 1 was the murder on 28th June 1914 of Archduke Franz Ferdinand of Austria by a Serbian fanatic.
ii) Austria immediately declared War on Serbia.
iii) Serbia was with allied Powers like UK, France, and Russia. The Austrian attack on it made these allied powers to come to Serbia's rescue.
iv) Austria was allied with central powers like Germany and Italy. This marked the beginning of World War I.
v) The immediate cause for World War II was Hitler's invasion Poland as punishment for refusing to hand over the port of Danzig to Germany.
vi) Aggressive nationalism, imperialism, militarism, secret alliances and ideological failure of the league of nations were also major factors that led to the foundation of world wars.
vii) After the first world war, these causes continued to lead the way to the second world war. Other causes include dissatisfaction of Germany with the legacy of World War I.
viii) A large industrial complex had come into function which promoted the idea of wars between countries as the only solution to conflicts.
ix) Most of these causes are prevalent to the current situation as well. The nationalism in its extreme form can often infuse the feeling of superiority over other nation. This can create pride in oneself and hatred towards other.