I doubt the effectiveness of the French airforce (in 1940!!!), which was purely a land war orientated instrument for assisting the Army, not the Navy. Its aircraft were of mediocre quality and all were very short ranged and incapable of providing duration aircover on land, nor at sea. In this case the Regia Aeronautica performance was far better, though not always in cooperation with the Navy. At least the Regia Aeronautica had the strike-capability to attack targets at sea, which the French lacked.
That would be news to the French.
That would be news to the French 2.0.
Credit: Late 298 photo from Cols Bleus August 16, 1975 (This image comes from
Gallica Digital Library and is available under the digital ID
bpt6k9607455s)
The French had assorted contraptions like that one (^^^) buzzing around since WWI.
Credit: Loire 130 photo from L'Aerophile June 1944 (L'Aerophile magazine -
http://gallica.bnf.fr/ark:/12148/bpt6k65537820?rk=64378;0)
That one spotted fall of shot and conducted air sea rescue missions. Actually was better than the USN Seagulls, Kingfishers and Seamews. What can I say? The French had a talent for floatplanes.
Second: France could not deploy all its capital ships in the Mediteranean as the Atlantic was also demanding a strong presence in case another enemy, perhaps Germany, showed up. The Marine Nationale always had a split fleet, just as the USN always had one between its two seaborders and never could deploy all its assets in one local area. Even more interesting is that the main buildingyards and facilities were on the Atlantic coast and not the south of France. As such in 1940, the Maine National would in normal conditions get at its best a parity in capital ships in the Mediteranean, with the note that the French Bretagne class was quite obsolete already and the even older Courbet class was not longer considered fit for frontline duties. The newer Dunkerque class was available but tied to the Atlantic ports until the larger Richelieu class was entering service. (Unless you can arrange some sort of a deal between France and Germany for instance to take away such tensions as well.)
That is actually a good point because the French navy was stuck in schizophrenia mode between the world wars. (See Map).
Credit: (
https://www.naval-history.net/Map43Mediterranean.htm) and McPherson
Thing is that the French Marine National between the wars and especially between 1935 -1940 was focused on two types of navy. The one on the Atlantic coast of Metro France was a true battle fleet, the Force de Raid. Usually deployed at Brest, St Nazaire and la Rochelle, this was a surface action group built around France's biggest fastest meanest longest ranged ocean going warships and was intended to operate in the North Atlantic. You'll find the Dunkirks and the Algerie and the Magadores and such operating from this region. Their mission was to protect France's sea-lines-of-communication to west Africa and to operate forward into the English Channel and North Sea if it became necessary to thump the Kriegsmarine. They were very good at their missions.
In the Mediterranean Sea, it is a different navy. Here the French were Italy oriented. Their assets were SLOW. The Bretagnes and Courbets were 10 m/s (20 knot) WWI dinosaurs that were unable to even catch their WW I Italian counterparts. When the Italians started to modernize the Cavours,and Dorias; well that was NTG. The French had to do something but modernizing a junkheap like a Bretagne was expansive and expensive and for technical reasons the Courbets were just not worth the francs.
So the French navy went schizo. They designed short ranged and extremely fast super destroyers and a series of light and heavy cruisers that would plow ahead of their battleline of Bretagnes and brawl with their Italian opposites to get in close to deliver massed torpedo attacks upon the Italian battle-line to cripple one or two battleships and then the Bretagnes would slowly move in and polish the cripples off. If that sounds familiar, it is what the Japanese called "reduction and attrition".
Fine, but the Italians are still faster and they can raid SLOCs between France and Algiers. The French answer to that one was AIRPOWER and fortified ports. Yup, we're back in the era of Endicott and the US fortress port system out of which convoys move from port to port in short little hops to find safe haven behind coast defense artillery. The French calculated (Correctly) that the Italian fleet sortie radius was no further west from La Spezia, and Naples than Minorca and Ibiza. Guess what the two terminii of that convoy route were? Toulon and Mers el Kebir. Heavily fortified with strong coastal and air defenses. If the Italians are going to hit that route they have to come AT TOULON. It is the end their fleet can reach.
Another thing is the Anti aircraft capabilities on both navies as both were known to have mediocre AA capabilities in all its ships at best. This might be tending to the Italian superiority in local Italian controlled waters given its far better suited Regia Aeronautica in anti shipping operations. This would mean the Italians could hang in the back and let the french come out to them, which was their main strategy from the start in WW2 as well. Once at sea, the French would have to face the airforce of the Italians unprotected, due to their lack of training and preparation of combined airforce and navy operations. (Only the Japanese actually had such a combined naval and airforce as their Naval Airforce was an independent unit compared to the Army airforce).
Regia Aeronautica aircraft were slightly longer ranged than French aircraft but let us not exaggerate. Both air forces could operate off their coasts with aircraft that were fairly well matched. Italian aerial torpedo plane forces do not come into their own until AFTER 1940. (
@Palantir covers this.) The French already have a formidable seaplane torpedo force in place since 1935. We don't see it in WWII because the French MN has no-one Italian to fight for more than two weeks in the Med. and their naval air force was kind of busy up north.
Please note that OTL, the MN concentrated it's heavy assets in Mers-El-Kébir in late April and early May. It's probably because they thought that Toulon was too exposed to air threats. Incidentally, I think it put MN's battleships more at risk of MAS types special ops than at Toulon. Mers-El-Kébir has only one choke point protecting the anchorage, while Toulon has three, in a row.
That is 1940 and that move is to get away from the Germans from the north, who were bearing down kind of fast. Additionally, while I agree that Mers el Kebir is an open invitation for a mini-sub attack, it is not likely to be the basing mode for the French pre-war in this ATL or a target for an Italian surprise attack. It is out of the Italian sortie range if they try to pull a Trident which is what Campagnalia was yelling at Mussolini to do in 1940. If the Moose was going to take the Italians into war then Toulon was their best shot at an early Marine National knockout punch. Since this timeline is kind of 1935-1940ish I went with what the French and Italians had at that time (~1937.).
BTW, you covered the airpower situation quite well.
Except that, in May 40, the Marine Nationale had concentrated it's battleships in the Med. There were 2 Bretagne and 2 Dunkerque in Western Med and 1 Bretagne in Eastern Med. You're right that the 2 Courbet were death traps in a battleship fight at the time, that's why they were still in Brest and Cherbourg to support land operations. So, when Italy entry in the war became probable in the spring 40, the MN concentrated it's assets in the Western Med and deferred to the RN for the rest of the world. I seem to recall that there was some sort of agreement between France and the UK on this. I don't see why it would go otherwise here.
The opening naval move is a surprise attack from peacetime. It really is the only chance either navy has for a decision at sea. They are too evenly matched otherwise. Deployments (see above) are based on the Anglo-French coverage agreement and did not change until May 1940 when French naval intelligence got wind that the Italians were up to something.
You're right that the French Army was not very efficient in 1940, but it's still far better equipped and far more functioning than the Italian Army. And the French have the industrial capacities and the cash to buy in the US to reduce their short comings, given time. The French can mobilize almost twice as much men than the Italians (from a lower manpower base) and arm them, but, the biggest element in favor of a stalemate is the Alps and the rough terrain, negating most of the French advantages.
Expect a bombing campaign and siege warfare mountain style. Caporettio; only far worse.
There will be a second land front in North Africa which will be far more active and mobile than in the Alps. There, the French will have the advantage, and I think that most of the naval war will concentrate in convoys warfare. But neither France nor Italy can block convoys of the other for Africa, only block some ports of the other.
I think it is Toulon or bust for Italy. Going the other way? Goodbye La Spezia. French surprise attack looks a lot more like Karachi every time I wargame it. The French gun advantage in such a surprise is crushing.
Here, French North Africa infrastructure gives far more possibilities as the French can simply run convoys in the Atlantic to Morocco and then trains to Tunisia. To the contrary, if Tripoli is blockaded, the Italian will loose anything west of Syrte in the medium run. It's simply far too difficult for them to support their forces from Benghazi, specially if the French have the advantage in manpower, mobility material and, most likely, air power.
Out of French sortie range. It works both ways, you know, that sortie range limit? They, the French, will have to do something about Sardinia and SICILY. I note that the British tried and NEVER could break the Italian lifeline to Libya until Anglo-American TORCH solved the problem overland. That is a HUGE logistics and terrain land warfare nightmare.