Typical answers would say, "Well, that depends upon how Italy enters the war."
Presuming the OP just wants hand-wavium, everything the same as OTL other than Mussolini calls in his merchant marine and then declares war, it probably helps the Axis presuming Manstein's plan is still followed. France will commit more forces to defending the French Alps and Britain is tied down even more in North Africa. In fact, this is where Italy stands to lose pretty badly before the attack on France. The good news is this butterflies away any invasion of Greece in the meantime.
Anyway without hand-waving ?Presuming the OP just wants hand-wavium, everything the same as OTL other than Mussolini calls in his merchant marine and then declares war,
So... Mussolini waits until say 1 November, which allows a month for Italian ships to return home. By that time, the Phony War is in place. Fall GELB doesn't start until May 1940, six months later.
What do France and Britain do in the meantim? ...The Allies can march into Italian East Africa and Libya. Other targets include the Dodecanese Islands and the Pelagic Islands. There's an interesting situation with Corsica and Sardinia, which are separated by only about 20 km. Also, Corsica is only about 50 km from Elba, and 250 km from Rome. There should be a lot of air combat. The French Air Force is seriously hosed at this time; having to fight might expose some of its weaknesses.
It would be interesting to see what plans the French military had for war with Italy. Also what plans Italy had for war with France; did Italy plan to invade Corsica?
I don't think the Dyle plan changes honestly. As I said before, Italy is a sideshow and the Wallies cannot afford to drain too many resources as Germany is the real focus.If France and Britain are busy mopping up Italian possessions during the winter 39-40 and operations last easily until summer of 40 we could see a less aggressive Dyle plan for the western front, which could have huge impact on success of the Battle of France.
Dyle plan was adopted despite considerable opposition within French and British army. The Italian declaration of war and thus need to commit more forces at Italian border and in colonies, could tilt the scales towards Escault plan, at least until the operations in colonies are concluded.I don't think the Dyle plan changes honestly.
So... Mussolini waits until say 1 November, which allows a month for Italian ships to return home. By that time, the Phony War is in place. Fall GELB doesn't start until May 1940, six months later...
It would be interesting to see what plans the French military had for war with Italy. Also what plans Italy had for war with France; did Italy plan to invade Corsica?
But why should Greece join the Axis? They didn't IOTL even after France fell.
Dyle plan was adopted despite considerable opposition within French and British army. The Italian declaration of war and thus need to commit more forces at Italian border and in colonies, could tilt the scales towards Escault plan, at least until the operations in colonies are concluded.
I forgot something. If Mussolini enters the war in November 1939, he has to have A Plan. That is, he has to intend to get something, probably by conquest. His OTL decision in 1940 was a spur-of-the-moment move to cash in on what appeared to be a fleeting opportunity. This is a deliberate step.
I forgot something. If Mussolini enters the war in November 1939, he has to have A Plan.
Hood, Renown, Repulse, Courageous, Glorious and Furious with heavy cruisers, flak cruisers and cruiser minelayers smash the Italian Fleet at anchor, and leave the seaways full of mines and sunk merchantmen.
Japan watches with interest.
The French fleet was split up. Essentially, Italy would have to do a divide and conquer campaign, beating the French at sea and then occupying Corsica. So, the ATL "Pearl Harbor" would be againt Toulon. Its only about 200 km from the Italian border, so I'd imagine the entire Italian airforce would have to be involved with a risky fleet action which pretty much encompasses the entire Italian navy, other than ships they need to land soldiers and destroyers for the taking of Corsica.
Yes, this is not a great airforce, but I presume the Italians had working torpedos and we know how Swordfish biplanes damaged the Italian fleet OTL.
The Italian fleet then engages the French fleet as they now appear over the horizon, destroying them in port. The fleet then sails to Corsica, where Italy's destoryers and merchant marine land a sizeable force to take Corsica, which pretty much surrenders after a few days.
At this point, everything depends upon the Franco-British reaction, which I presume, would be a combined British-French fleet. The Italian fleet hangs back and depends upon aircraft sent to Sardina (an unsinkable aircraft carrier!) to act as an air to their navy. If the Wallies engage, they will lose due to having no airpower to bring to bear in the battle. If they don't, Italy looks way better ITTL but the French and British then focus on taking Italy's North African possessions.
ITTL Greece joins Axis after France falls and after Yugoslavia joins the Axis (i.e. Axis diplomacy in early 1941). Italy's earlier involvement in the war butterflies away the Italian Balkan invasions.
I think Plan E was replaced by Plan D simply because of Belgian preparations. Italian entry into the war does not change the amount of men France will commit to defense against Germany. France was not eneregtic in WW2 and they were not going to invest themselves into a peripheral campaign against Germany and employ a more flexible defensive strategy. France's thinking was predicated upon not repeating WW1. Their goal was to keep Germany of France's soil and their planning showed it. So, I don't see them changing anything major, simply because they do not take a main thrust through the Ardennes seriously.
I agree, and I simply just cannot see what it is. I mean, crazier things have happened. Powers declare war "like gentlemen" and simply just start fighting when and where they can. Germany did this to the USA. I mean, Germany could have simply started sinking US ships without declaring war. So, even in WW2 we see the Axis making moves like this.
Nevertheless, it does seem odd other than a POD like "Mussolini hits his head way too hard and DOW for no reason." He was not ready in Africa to invade French AND British possessions, so that is definitely a no go. A Mediterranean strategy is the only one that makes sense. If I really had to pull a target out of my butt for the sake of the OP, I'd say Corsica. It's an Italian possession originally, it's somewhere the British cannot project manpower (though eventually they could do fleet actions), and there is more propaganda value than Malta (though Malta would prove to be a better strategic target...but Italy was not going to go to war over a tiny island.)
However, for Italy to pull this off, you would need an Italian Pearl Harbor.
According to WIKI:
The Regia Marina had six battleships with which to contend for control of the Mediterranean, the four most modern of which were being re-fit at the outbreak of the war. In addition to the six capital ships, the Italians had 19 cruisers, 59 destroyers, 67 torpedo boats, and 116 submarines.
The French Fleet (WIKI):
The French fleet had seen little fighting during the Battle of France and was mostly intact. By tonnage, about 40 percent was in Toulon, near Marseilles, 40 percent in French North Africa and 20 percent in Britain, Alexandria and the French West Indies.
The French fleet was split up. Essentially, Italy would have to do a divide and conquer campaign, beating the French at sea and then occupying Corsica. So, the ATL "Pearl Harbor" would be againt Toulon. Its only about 200 km from the Italian border, so I'd imagine the entire Italian airforce would have to be involved with a risky fleet action which pretty much encompasses the entire Italian navy, other than ships they need to land soldiers and destroyers for the taking of Corsica.
Italian airforce (Wiki):
When World War II began in 1939, Italy had the smallest air force among the three major Axis powers. With a paper strength of 3,296 machines, only 2,000 were fit for operations, of which just 166 were modern fighters.
Yes, this is not a great airforce, but I presume the Italians had working torpedos and we know how Swordfish biplanes damaged the Italian fleet OTL.
So, in short, the Italian plan is to throw everything they have at Toulon, other than a few long range bombers being deployed for actions against Corsica. Just like the Germans did with Barbarossa, the Italians deploy their airforce just before dawn as their fleet closes in. To get the timing right would be nearly impossible, so I'd guess the air force already awakens the sleeping French giant and for Italy's sake does a lot of damage. The French, with most of their assets deployed against the Germans, put up good resistance but cannot stop the waves of air attacks.
The Italian fleet then engages the French fleet as they now appear over the horizon, destroying them in port. The fleet then sails to Corsica, where Italy's destoryers and merchant marine land a sizeable force to take Corsica, which pretty much surrenders after a few days.
At this point, everything depends upon the Franco-British reaction, which I presume, would be a combined British-French fleet. The Italian fleet hangs back and depends upon aircraft sent to Sardina (an unsinkable aircraft carrier!) to act as an air to their navy. If the Wallies engage, they will lose due to having no airpower to bring to bear in the battle. If they don't, Italy looks way better ITTL but the French and British then focus on taking Italy's North African possessions.
I'll leave it to others to speculate whether Italy then strikes at Malta with the goal of securing their logisitics to Libya where they play defense and await the German invasion of France.