Why did it fail? It can be prevented by them getting what they were promised by Britain, France and Russia.
Well Wilson declaration that the previous 'secret treaty' were null and void and other agreement need to be found...so open the can of worm of the negotiation between Italy and the newborn Yugoslavia, plus is general treatment of the italian delegation (who diplomatically speaking had problem on his own) surely helped a lot but was not the only factor.
The march of Rome was a gigantic bluff as the fascist were not ready for an armed confrontation with the military and the fascist leadership (except Benny) was riunited in a single place, so the goverment had the big change to cut the head of the movement in a single stroke, so if the King decide that in the end Benny can't be trusted or controlled...the fascist are gone, sure there will be riot and the need to clean some remnant but in general they will be history.
The socialist are the next in line for a forcefull takeover of the nation, but unlike the competition they don't have a single leader that can unify the various faction and many (like Matteotti) prefer to work with the system instead of totally breaking; say that expect a turbulent time for the italian political life, a year of two of general violence under a goverment directely nominated by the king.
