What was Mussolini's role in the outbreak of World War 2?

Benito Mussolini did not play a very direct role in the outbreak of WWII.  Italy did not start the war.  In fact, it did not even enter the war until Germany had already defeated France.  Therefore, we cannot say that Mussolini played a very large role in starting the war.

While Mussolini did not play a direct role in starting the war, he contributed to it in three indirect ways.  First, Mussolini was an inspiration...

Benito Mussolini did not play a very direct role in the outbreak of WWII.  Italy did not start the war.  In fact, it did not even enter the war until Germany had already defeated France.  Therefore, we cannot say that Mussolini played a very large role in starting the war.

While Mussolini did not play a direct role in starting the war, he contributed to it in three indirect ways.  First, Mussolini was an inspiration for Hitler and the Nazis.  Mussolini and his fascist movement took power in Italy more than a decade before the Nazis came to power in Germany.  The Nazis shared many beliefs with the Italian fascists and the rise of fascism in Italy helped inspire Hitler and the Nazis to believe that they could take power in Germany.  By helping Hitler come to power, Mussolini helped start WWII.

Second, Mussolini helped bring about WWII by allying Italy with Germany.  With Italy as an ally, Germany did not have to worry about having to fight a war in the south when it started WWII.  This allowed Hitler to be more confident about invading Poland and then France.  He knew that he would not have to fight two enemies at once.  By giving Hitler this security, Mussolini helped start WWII.

Finally, and perhaps most importantly, Mussolini helped to discredit the League of Nations, which was supposed to help keep the peace after WWI.  One of the things the League was supposed to do was to prevent countries from fighting wars of aggression against one another.  However, when Italy invaded Ethiopia in 1935, the League did nothing.  This helped show that the League was really powerless and that there was nothing to stop an aggressive country from taking what it wanted by military force.  By helping to expose the weakness of the League of Nations, Mussolini helped to convince Hitler that he could take what he wanted through the use of military force.  This, too, helped to start WWII.