I think one has to keep in mind that the French and Italians were really not gearing their navies up for a 'Jutland' style battle, and didn't give a whole lot of though to having proper battle lines. Italy, when creating its force structure in the 1920s, pretty much left behind the concept, which figured heavily in procurement and battleship design. Though they paid lip service to the idea of using their battleships as an 'armored core' for the fleet to fall back upon, they more or less considered the ships useless (far too slow, especially because of their horrific vulnerability to bombs and torpedoes). The fleet was to be based on their cruiser forces - this was much of the reason behind why the Italians deliberately cheated the WNT when it came to the Zara-class - they wanted an armored core to their cruiser fleet, which would give them a decisive advantage over their French counterparts. The French had a similar, though not so radical view - they still considered their battleships viable for use as a fallback point for their cruisers, which is partly why the spent so much effort upgrading them compared to the Italians (this was also partly due to the fact that, by 1920, their battleships were starting to become out-classes as they fell behind in adopting technology such as directors, or taking steps to increase the elevation of their guns. Thus, the 340mm Bretagne-class only became able to rival the ranges of the Italian 305mm dreadnoughts after their refits from 1924 to 1927).
The Dunkerque-class spawned out of the line of development of fast 305mm battleships intended to deal with these Italian heavy cruisers, and the Italian rebuilding of the Cavour-class was largely in response to that. The second Dunkerque prompted the Littorio-class (which spawned out of the designs of treaty battleships that had to be able to reach 30 knots so they could support the cruisers), which prompted the Richelieu-class in response, and things evolved in a tit-for-tat manner from there - but once again, neither party was looking at things from the point of view of having a proper fleet (both navies were building themselves wildly heterogeneous battle lines).
If it came to a confrontation between the two of them, the most likely course of action would be cruiser-based warfare to strike at each other's lines of communication to Africa, with the battleships acting in support of such a method of conflict. I highly doubt either would seek a 'Jutland'-style action, unless one sought to lay a trap for another. Things would settle into a war of attrition, at least until the battleships made their debuts - which becomes a major turning point for the war.
Assuming we're looking at a conflict starting in 1940, the Italians are initially at a disadvantage. The French have the trio of Bretagne-class battleships available, and the two Dunkerque-class battleships. The former are not a huge threat - unable to catch any major Italian warships, and wholly inferior to the Cavour-class in firepower, fire control, protection, and of course, speed. Any action between them would be horrifically one-sided. However, the Dunkerque-class is faster and better protected than the Cavour's, likewise have a modern fire control system, and have comparable firepower - overall, more than a match for the Italian battleships, especially Strasbourg.
Such a balance of power would not shift until the end of the summer of 1940, as Littorio, Vittorio Veneto, and Caio Duilio are mostly worked up and operational as of September 1940 (Andrea Doria, completed later, would not become fully operational until about February 1941). The addition of another 'rebuild' to the Italian fleet is significant, especially since the Caio Duilio-class were significantly better than the Cavour-class (superior secondary & AA battery, superior fire control for all batteries), but the addition of the two Littorio's gives the Italians a decisive advantage, since it allows them to send out their cruiser forces with battleship support, and without slowing down the operation of the fleet as the rebuilds would.
The French could not match this until Richelieu entered service, and that wasn't going to be for a while - her 'completed' state in June of 1940 was very much incomplete and she still needed more work before she could be considered finished. Tack on time to work up and become fully operational, plus fixing all her issues... she may not enter service until 1941, and Jean Bart in 1942, which point the Italians, if Impero is not moved as was done historically, will have her in service (mid-1941), with Roma following in mid 1942. Clemenceau may have only just launched by then...
Shifting down a peg, the Italian heavy cruiser force likewise greatly outmatches the French force - the Trento-class (2) and Bolzano are capable of resisting up to 155mm fire at combat ranges (14,000 meters+), and the Zara-class (4) will be able to resist 203mm shellfire to such ranges too. In contrast, the only French cruiser that isn't cripplingly vulnerable to Italian 152mm fire (nevermind 203mm) is the excellent Algérie (which is also the only French heavy cruiser protected by armor steel, not construction steel...). It is only with the light cruisers that things become more comparable, since the French have access to the six excellent La Galissonnière-class - the only light cruisers the Italians have that are better are the Abruzzi twins. Though faster, the Montecuccoli (2) and Duca d'Aosta-class (2) would be fighting at a disadvantage due to having lesser firepower and armor protection (while the Abruzzi-class are resistant to 152mm fire at any combat range, the other two are only resistant at around 13,000 to 13,500 meters). The six modern French light cruisers, however, could have shrugged off the APC from the 152/53 M1929 at 11,000 meters (and probably the 152/55 at 1-2 km further). That being said, the Émile Bertin (1) and Duguay-Truoin (3) classes are essentially unarmored.
It's a bit hard to speculate on aerial and submersible warfare - so much of how the RM's (and RA's) capabilities developed depended on their environment during the war. One of the reasons Italian submarines were as successful in the Atlantic as they were was the help of training with the German U-boat arm, and likewise many tactics were revised based on the initial lethality of RN ASW capabilities. While I suspect Mediterranean subs would have more success given there'd be French traffic around, Italian submarines might not be pressed enough to evolve as much as they did. British ASW capabilities were very good. French ASW capabilities were negligible. Likewise, British submarines helped push the Italian ASW effort. French submarines in action... had their moments, but were arguably in a worse place than their Italian counterparts;
(From On Seas Contested, a book mentioned earlier in this thread. The relevant chapter is written by John Jordan).
Likewise, I don't think the French would have been nearly the air threat the British were, or the AA threat. French aerial torpedoes had sold performance, but were weaker than their British or Italian counterparts (40cm 26DA had a warhead of 144 kg TNT, versus 176 kg TNT from the 18" Mk.XII or 200 kg TNT of the F/Si 200/450).], and afaik only had a contact warhead - making any sort of Taranto-style action impossible. That's an important thing to note, because the Italian ships tended to be very difficult to torpedo at sea - even if the RM could not secure air cover for themselves, they did take the torpedo-bomber threat very seriously (and had since 1918), and methods of dodging aerial torpedoes was practiced extensively in the interwar period. The first real luck the British had at sea was during the Gavdos action (Vittorio Veneto and Pola), and even then that mostly came as a result of repetitive waves of attack in combination with conventional bombers, something I'm not sure the French could pull off.
A final note - the French were far more vulnerable to Italian aircraft attack than their British counterparts. British formations at sea were often protected by the aegis of radar-vectored fighters operating from carriers, and even when that wasn't the case, generally had a fair amount of AA on them, with major warships having various numbers of 4"/45's and 40mm pom-poms. French AA and AA fire control were not really up to part - the best heavy AA guns available (100mm/45 Mle 1930 and 90mm/50) were available on few ships (the 100mm only on Richelieu and Algérie, the 90mm on three heavy cruisers and the seven most modern light cruisers), with everything else relying on the borderline useless 75mm/50 Mle 1924. Fire control systems were generally not that good (Mle 1934 system for the 152mm guns had a better maximum target speed of 576 kph, but like earlier systems could not handle targets unless they were in level flight. The Mle 1934 doesn't seem to have much testing in action, but the Mle 1930 that equipped most ships was considered unreliable, to the point where local control was preferred by crew in action), and for closer-ranged defense the ships had very limited firepower - the only available medium-range cannon was the 37mm/50 Mle 1925, which was an abysmal 'semi-automatic' weapon with a service rate of fire of just 15-21 rpm.
I wouldn't expect such shortcomings to be a huge issue in, say, mid-1940 (since the RA was still practicing high-alt, level bombing with 50 kg, 100 kg, and 250 kg bombs), but once torpedo-bombers are introduced I'd expect the losses to start rising. Historically, the first torpedo-bomber unit (Reparto Sperimentale Aerosiluranti, or Experimental Torpedo-Bomber Unit) was formed on 25 July 1940 and became operational on 5 August. Despite there only being four of them (originally five, but one was lost on their first mission), over a four-month period the four torpedo-bombers were able to score blows on three British cruisers. With much less effective AA fire from French ships and less effective fighter screens, one can only imagine how much more successful they might have been.
----------------------------------------------------------------
Long story short - if a war erupted in 1940, I'd expect it not to see a Jutland-style clash. More likely, it would be an escalating game of fast surface strike groups as they attempt to raid, counter-raid, or defend against enemy traffic and raiders (the target for the Italians being the Toulon-Tunis route, the target for the French being the Taranto-Tripoli or Naples-Tripoli route. The Italians would play conservatively against the French battleships until Littorio and Vittorio Veneto enter service, then become aggressive in an attempt to take advantage of their superiority in firepower. In the meantime they'd be relying on submarines and aircraft for offensives, which I suspect the French would become more reliant on until/if they can balance out the battleship question.
The Dunkerque-class spawned out of the line of development of fast 305mm battleships intended to deal with these Italian heavy cruisers, and the Italian rebuilding of the Cavour-class was largely in response to that. The second Dunkerque prompted the Littorio-class (which spawned out of the designs of treaty battleships that had to be able to reach 30 knots so they could support the cruisers), which prompted the Richelieu-class in response, and things evolved in a tit-for-tat manner from there - but once again, neither party was looking at things from the point of view of having a proper fleet (both navies were building themselves wildly heterogeneous battle lines).
If it came to a confrontation between the two of them, the most likely course of action would be cruiser-based warfare to strike at each other's lines of communication to Africa, with the battleships acting in support of such a method of conflict. I highly doubt either would seek a 'Jutland'-style action, unless one sought to lay a trap for another. Things would settle into a war of attrition, at least until the battleships made their debuts - which becomes a major turning point for the war.
Assuming we're looking at a conflict starting in 1940, the Italians are initially at a disadvantage. The French have the trio of Bretagne-class battleships available, and the two Dunkerque-class battleships. The former are not a huge threat - unable to catch any major Italian warships, and wholly inferior to the Cavour-class in firepower, fire control, protection, and of course, speed. Any action between them would be horrifically one-sided. However, the Dunkerque-class is faster and better protected than the Cavour's, likewise have a modern fire control system, and have comparable firepower - overall, more than a match for the Italian battleships, especially Strasbourg.
Such a balance of power would not shift until the end of the summer of 1940, as Littorio, Vittorio Veneto, and Caio Duilio are mostly worked up and operational as of September 1940 (Andrea Doria, completed later, would not become fully operational until about February 1941). The addition of another 'rebuild' to the Italian fleet is significant, especially since the Caio Duilio-class were significantly better than the Cavour-class (superior secondary & AA battery, superior fire control for all batteries), but the addition of the two Littorio's gives the Italians a decisive advantage, since it allows them to send out their cruiser forces with battleship support, and without slowing down the operation of the fleet as the rebuilds would.
The French could not match this until Richelieu entered service, and that wasn't going to be for a while - her 'completed' state in June of 1940 was very much incomplete and she still needed more work before she could be considered finished. Tack on time to work up and become fully operational, plus fixing all her issues... she may not enter service until 1941, and Jean Bart in 1942, which point the Italians, if Impero is not moved as was done historically, will have her in service (mid-1941), with Roma following in mid 1942. Clemenceau may have only just launched by then...
Shifting down a peg, the Italian heavy cruiser force likewise greatly outmatches the French force - the Trento-class (2) and Bolzano are capable of resisting up to 155mm fire at combat ranges (14,000 meters+), and the Zara-class (4) will be able to resist 203mm shellfire to such ranges too. In contrast, the only French cruiser that isn't cripplingly vulnerable to Italian 152mm fire (nevermind 203mm) is the excellent Algérie (which is also the only French heavy cruiser protected by armor steel, not construction steel...). It is only with the light cruisers that things become more comparable, since the French have access to the six excellent La Galissonnière-class - the only light cruisers the Italians have that are better are the Abruzzi twins. Though faster, the Montecuccoli (2) and Duca d'Aosta-class (2) would be fighting at a disadvantage due to having lesser firepower and armor protection (while the Abruzzi-class are resistant to 152mm fire at any combat range, the other two are only resistant at around 13,000 to 13,500 meters). The six modern French light cruisers, however, could have shrugged off the APC from the 152/53 M1929 at 11,000 meters (and probably the 152/55 at 1-2 km further). That being said, the Émile Bertin (1) and Duguay-Truoin (3) classes are essentially unarmored.
It's a bit hard to speculate on aerial and submersible warfare - so much of how the RM's (and RA's) capabilities developed depended on their environment during the war. One of the reasons Italian submarines were as successful in the Atlantic as they were was the help of training with the German U-boat arm, and likewise many tactics were revised based on the initial lethality of RN ASW capabilities. While I suspect Mediterranean subs would have more success given there'd be French traffic around, Italian submarines might not be pressed enough to evolve as much as they did. British ASW capabilities were very good. French ASW capabilities were negligible. Likewise, British submarines helped push the Italian ASW effort. French submarines in action... had their moments, but were arguably in a worse place than their Italian counterparts;
The performance of France’s large submarine force was disappointing. The coastal submarines deployed to patrol areas in the North Sea during the early months of the war achieved nothing. In the 1,500-tonne fleet boats, there was still inadequate attention to habitability, and they never attained their designed patrol endurance of thirty days. There was insufficient ventilation in the early boats, supplies of bottled oxygen were inadequate, and fresh stores were provided for the equivalent of two and a half days (a defect corrected by the installation of additional refrigeration during later refits). Wartime experience was to reveal that insufficient attention had been given to protecting the submarines against the shocks likely to be experienced during depth charging. There were problems with watertight hatches and battery integrity; electrically operated systems such as lighting circuits and the external torpedo mountings frequently failed because switchboards and control systems were not seated on flexible mountings.
(From On Seas Contested, a book mentioned earlier in this thread. The relevant chapter is written by John Jordan).
Likewise, I don't think the French would have been nearly the air threat the British were, or the AA threat. French aerial torpedoes had sold performance, but were weaker than their British or Italian counterparts (40cm 26DA had a warhead of 144 kg TNT, versus 176 kg TNT from the 18" Mk.XII or 200 kg TNT of the F/Si 200/450).], and afaik only had a contact warhead - making any sort of Taranto-style action impossible. That's an important thing to note, because the Italian ships tended to be very difficult to torpedo at sea - even if the RM could not secure air cover for themselves, they did take the torpedo-bomber threat very seriously (and had since 1918), and methods of dodging aerial torpedoes was practiced extensively in the interwar period. The first real luck the British had at sea was during the Gavdos action (Vittorio Veneto and Pola), and even then that mostly came as a result of repetitive waves of attack in combination with conventional bombers, something I'm not sure the French could pull off.
A final note - the French were far more vulnerable to Italian aircraft attack than their British counterparts. British formations at sea were often protected by the aegis of radar-vectored fighters operating from carriers, and even when that wasn't the case, generally had a fair amount of AA on them, with major warships having various numbers of 4"/45's and 40mm pom-poms. French AA and AA fire control were not really up to part - the best heavy AA guns available (100mm/45 Mle 1930 and 90mm/50) were available on few ships (the 100mm only on Richelieu and Algérie, the 90mm on three heavy cruisers and the seven most modern light cruisers), with everything else relying on the borderline useless 75mm/50 Mle 1924. Fire control systems were generally not that good (Mle 1934 system for the 152mm guns had a better maximum target speed of 576 kph, but like earlier systems could not handle targets unless they were in level flight. The Mle 1934 doesn't seem to have much testing in action, but the Mle 1930 that equipped most ships was considered unreliable, to the point where local control was preferred by crew in action), and for closer-ranged defense the ships had very limited firepower - the only available medium-range cannon was the 37mm/50 Mle 1925, which was an abysmal 'semi-automatic' weapon with a service rate of fire of just 15-21 rpm.
I wouldn't expect such shortcomings to be a huge issue in, say, mid-1940 (since the RA was still practicing high-alt, level bombing with 50 kg, 100 kg, and 250 kg bombs), but once torpedo-bombers are introduced I'd expect the losses to start rising. Historically, the first torpedo-bomber unit (Reparto Sperimentale Aerosiluranti, or Experimental Torpedo-Bomber Unit) was formed on 25 July 1940 and became operational on 5 August. Despite there only being four of them (originally five, but one was lost on their first mission), over a four-month period the four torpedo-bombers were able to score blows on three British cruisers. With much less effective AA fire from French ships and less effective fighter screens, one can only imagine how much more successful they might have been.
----------------------------------------------------------------
Long story short - if a war erupted in 1940, I'd expect it not to see a Jutland-style clash. More likely, it would be an escalating game of fast surface strike groups as they attempt to raid, counter-raid, or defend against enemy traffic and raiders (the target for the Italians being the Toulon-Tunis route, the target for the French being the Taranto-Tripoli or Naples-Tripoli route. The Italians would play conservatively against the French battleships until Littorio and Vittorio Veneto enter service, then become aggressive in an attempt to take advantage of their superiority in firepower. In the meantime they'd be relying on submarines and aircraft for offensives, which I suspect the French would become more reliant on until/if they can balance out the battleship question.
Last edited: