Mussolini made the trains run on time.
This was his great accomplishment.
His mistake was joining Hitler, before that he did a lot of good for Italy and tried to modernize the country, making education compulsory and moving the country away from basically still being a feudal state.
The Italian Fascists repeatedly told the Germans they were not ready for war, and would need at least another 5 years to modernize their military. They had also spent massive amounts in the Ethiopian War and the Spanish Civil War and were facing heavy sanctions. The Germans said they had no plans for a European war. Then they invaded Poland.