Was Germany the cause of World War I?
In answering this question, I assume you are asking if Germany was responsible for the start of World War I in 1914. There were many factors that led to the start of World War I in 1914.
The specific event that led to the start of World War I was when Franz Ferdinand was assassinated by a group of Serbians. Austria-Hungary made a series of demands on the government of Serbia, and when the government of Serbia couldn’t meet all of the demands, Austria-Hungary declared war on Serbia. This declaration of war was followed by Russia declaring war on Austria-Hungary.
The reason why Germany had to accept the blame for starting World War I was that before Austria-Hungary declared on war Serbia, they asked Germany if they would support Austria-Hungary if another country declared war on Austria-Hungary. Since Germany agreed to support Austria-Hungary, the Allied leaders insisted Germany accept responsibility for the war in the Versailles Treaty.
Thus, Germany had some role in the events that led to the start of World War I. However, they weren’t the only country responsible for the beginning of this war.