Erich is right about the mines and the snipers. The Germans bloody mined the whole city of Naples and it took the British sappers months to clear it up!
And why don't we start by discussing who had the great idea to invade Italy from the very bottom and coming all the way up in the worst terrain in the world for attackers?! However made that decision didn't listen to the greatest military genious of contemporary era who clearly said: "Italy is a boot; therefore, the best thing is to invade the north, cut his neck, isolate the rest of the country and smother the defender".
It is an axiom. It can't be more true or clearer! BUT, we must take into account what did the Allies thought THEN? I'm sure they had good reasons...?