How would an Entente invasion of Sicily and Southern Italy go if Italy joined the central powers.

[lukedalton]

If the Allies want to attack Italy, they can cross the Alps and attack northern Italy directly. Northern Italy is more valuable and industrialized. Crossing the Alps is difficult, but not as much as trying an amphibious invasion when amphibious doctrine has not been invented yet (the big problem at Gallipoli) and they don't even have command of the sea.

A direct attack through the terraim most easy to defend on the continent with the addition of horrible weather and climatic condition will not a good idea; unless you want lose a lot of men basically while an invasion of Sicily will be Gallipoli at the nth power, it will always better than try a direct attack from France towards Italy

 

[VoidStalker]

Poorly. From the OP it sounds like Italy joining in 1914? In that case the French troops on the border do not get pulled north to hold the Germans which means they do better in 1914 in the West, in addition you now have to face the Italian army and freeze troops in French Africa to face Italian troops in Libya. While I expect Libya to fall to do so you are diverting troops from other theaters. And because they would likely want to secure Libya before moving on to Sicily or Southern Italy we are looking at 1915 operation. Along the same line there were no free troops in 1914 (hence why Gallipoli was a 1915 op) due to demands of the Western front.

Honestly, with the need to take Italian colonies as well in addition to needing troops in the Alps plus I see no way the Serbian army escapes in 1915 with both the AH and Italian navies possessing naval bases close by (subs and light ships would be really bad on an evac) so you don't have those troops to call on either. Bulgaria also probably jumps in early 1915 and with Austrian troops being able to be pulled from the Italian border and not dying and spending supplies fighting the Italians they are putting more pressure on Russia.

Any operation is likely late 1915 and running back line units with reduced artillery (not to mention older pieces) so I do not see it going well short of the Italians not opposing or relying on back line units as well. Though with Churchill I could see a proposal for a port closer to Rome to try and punch through there.

Also I remember reading about migrant workers from Italy helping with the harvests in southern France during 1914 though I am unsure which book that was as I read it a while back. Anyone familiar with a source? There was an article about immigrants in france during WW1 through JSTOR but I do not have an account right now to access it: Immigrant Workers in France during World War I that might have some useful references