Germany
there population
It caused Great Britain and France to declare war on Germany.
because Germany were jelous of Britain
Because they caused World War 2 when their military invaded Poland.
The First World War was caused by a man in Germany getting shot. The Second World War was caused by Hitler not liking the Treaty of Versail.
Germany was forced to take all the blame for World War I as dictated in the Treaty of Versailles.
World War II officially began after Germany invaded Poland. The invasion of Poland caused England and France to declare war on Germany.
Germany. Germany caused Americans to be raged, and want President Woodrow Wilson to take action in the war, but he kept neutrality for a while, but then entered the war.
Germany invaded Poland
A blitzreig {lightning war} in Poland caused by Germany.
It is generally impossible to prove a negative. The question needs to ask about evidence that Germany caused World War 1.