Some historians have argued that the war was caused by the actions of Franz Ferdinand, Archduke of Austria. Ferdinand was assassinated by a Serbian nationalist in Sarajevo on June 28, 1914, and his death triggered a chain of events that led to war.
Other historians have argued that the war was caused by the actions of the German government. German leaders believed that they could win a quick and decisive victory against France and Russia, and they were willing to take the risk of war in order to achieve their goals.
Still other historians have argued that the war was caused by the actions of the British government. British leaders believed that they could prevent a German victory by intervening in the war on the side of France and Russia.
In reality, the causes of World War I were far more complex than any of these simple explanations. The war was the product of a long-term build-up of tensions between the major powers of Europe. These tensions were exacerbated by the rise of nationalism, the arms race, and the increasing competition for resources.