Could the Italian campaign have succeeded alone?

[Sertak]

The Italian Campaign was planned very frivoulously, since the beginning. The Allies' underestimation of Germans' reactions and abilities had become the total disaster for this operation, which may have become a successful one, if Anglo-American forces weren't so slow in their assault on the South.

 

[Baron von Feldspar]

Instead of the Ballad of the D-Day Dodgers the troops assigned to more northern sectors would be singing the Ballad of the Anzio Avoiders.

 

[Peter Cowan]

To echo Redbeard, to a large extent Italy was the only feasible option in 1943. There were insufficient Allied troops and landing craft in the UK for a cross chennel assault. Knocking Italy out of the war had one beneficial side effect not usually shown up in the troop numbers engaged. It meant that the Germans had to garrison or abandon large areas of the Balkans. It also showed Stalin that the Allies would fight in Europe.

As to it being a route into Germany / Austria - I doubt it. The alps and attached ranges are just too easily defensible and to drive towards Vienna via Slovenia would mean deploying huge numbers of troops to cover the flanks.

 

[merlin]

The problem with the Italian Campaign was that it wasn't planned early enough.
While the British were enthusiastic about it - it was their policy to encourage the Germans to spread their forces by attacks on their periphery - so leaving fewer forces for the 'cross-channel' campaign. However the Americans were suspicious of British intentions and sincerity about the invasion of France. Remember they wanted the cross-channel invasion in '42 - what a mess that would have been!
While we could wish, that the North-African campaign would have ended earlier; the decision where to go next should have been taken much earlier - Cassablanca? Whilst, it could be said that Sardinia shoud've been the target, it was always going to be the case that air-power considerations were over-riding. Thus the potential of air bases in Sicily was crucial. And likewise the Foggia airbase complex should have been the priority target in Italy.
Thus my alternative campaign would have been.
About four weeks after the capitulation at Tunis. Montgomery lands troops on the Sicilian shore. His unexpected landing meets little initial resistance but mounting German reinforcements hamper his progress. Nevertheless, air support is made available through captured airfields, which proves crucial in blunting Axis counter-attacks.
Several weeks later, another landing occurs this time its the Americans who take Tarranto. It is supported by a paratrooper landing near an important inland intersection (sorry don't have a map handy). Pattons' troops link up with the para's and rapidly drive north-west to cut the main Italian highway to Messina (& Sicily). While troops from another landing at Brindissi (just north of Tarranto) drive north on the eastern side of Italy.
The Germans caught off-guard react furiously to the threat to their rear throwing what re-inforcements they can to break the strangle hold the Americans have on their supply lines. Just when they think they may do it, another landing takes place - this time its the French with Canadian support (sorry but in this TL 'Dieppe' didn't happen), who invade and swiftly take Sardinia. This enabled the Allies to further interdict the Axis supply lines.
This Cannae like campaign, ended with Geman & Italian forces in Sicily surrendering - with their exit to the mainland cut off, and with Patton racing for the Italian airbases at Foggia. Meanwhile the French gave the Germans more problems by taking Corsica.
Now the Allies are in a better position, (subject to shipping) they have options where to go next.
North from Corsica to the South of France, land further up the western coast of Italy (not a good idea because of the terrian), head north along the eastern side of Italy, or across the Adriatic into Jugoslavia. Either way it gives the Germans problems - establish a defensive Italian line (but further north than in OTL), and the posittion is reached earlier than in the OTL.

Even in the OTL the situation would have been better if Mark Clark had stuck to orders - rather than wanting the personal glory of taking Rome!! The Germans would have been cut off, as it was they were able to escape to fight another day.