Answer: The immediate cause of World War I was the assassination of Archduke Franz Ferdinand of Austria-Hungary
Explanation: The assassination of Archduke Franz Ferdinand of Austria-Hungary by a Bosnian Serb nationalist triggered a diplomatic crisis. Austria-Hungary declared war on Serbia, and due to a complex web of alliances and treaties, many countries became involved. Russia mobilized to defend Serbia, which led Germany to declare war on Russia. France was then drawn in against Germany and Austria-Hungary. Germany attacked France by marching through Belgium, which pulled Britain into the war. Later, Japan, Italy, and the United States would enter on the side of the Allies. This series of events escalated into the full-scale conflict known as World War I
