The truth is that someone lied. Hitler? Mussolini? Or both?Yes, that's what happened. Mussolini is pretty much unlikable from both sides. From an Allied point of view, he's despicable and odious for siding with Hitler. But even from an Axis point of view, it could be argued that he was more of a liability than an asset for the Axis. Hitler had to divert some of his own forces to bail out Mussolini in Greece and North Africa.
They told that the war would last very few months, then the conflict expanded.
The people doesn't forgive liars.