There seems to be a trend that the French military establishment focused mainly on reactionary tactics in the prelude to both world wars, with the focus being on morale and massed charge in the prelude to World War 1 and the focus being on defensive forts in World War 2. In both cases the battles showed these tactics to be inefficient because of modern developments in tactics that rendered the old tactics useless, with the difference being that France managed to innovate its tactics (Pétain being one innovator) and win World War 1. Because of this, there seems to be a trend of a focus on reactionary tactics in the French Military during the time period, which I assume is related to some underlying factor in the culture of the French Military during this time period. This poses the question of what such factors were, and how they differed from Germany and England?
^ These answers I've given should be pertinent!
There seems to be a trend that the French military establishment focused mainly on reactionary tactics in the prelude to both world wars, with the focus being on morale and massed charge in the prelude to World War 1 and the focus being on defensive forts in World War 2. In both cases the battles showed these tactics to be inefficient because of modern developments in tactics that rendered the old tactics useless, with the difference being that France managed to innovate its tactics (Pétain being one innovator) and win World War 1.
I'd say this has more to do with perception than reality. With regards to the French Army before WWI, Simon House lays out it's ailments pretty well in his [thesis] (https://kclpure.kcl.ac.uk/portal/files/12690581/Studentthesis-Simon_House_2012.pdf) on the battle of the Ardennes. While a great emphasis was placed on the morale and fighting spirit of the soldiers, and on the offensive action of higher units, tactically the 1913 FSR was actually quite reasonable. It advised tactical defense or offense depending on the circumstances, and in the latter case stressed the need for 'fire superiority' and surete (reconnaissance, secure flanks, surprise) prior to an attack. Furthermore, while French artillery doctrine emphasized the 75 mm field gun, Joffre had already placed a order for modern, quick-firing heavy pieces in spring 1914, and there were at least some Rimailho howitzers available for Corps artillery. The real issue was a lack of proper training facilities and funding for training exercises, unlike the German Army, which, combined with the recent passage of the 3 year service law and the introduction of the new Field Service Regulations at the beginning of the year, saw the French Army sent into battle in 1914 with inadequate training and no clear doctrine to follow. Throw in equipment inadequacies that were just being addressed (uniforms, heavy artillery) and the C3 problems encountered by pretty much all the armies in 1914, and the French Army's disastrous performance in August 1914 is understandable. That said, the French had invested well in railways and aircraft, and their artillery doctrine paid off by ensuring that French Corps were light and mobile enough to disengage and shift their forces with great speed. This allowed Joffre to shift the weight of his armies from the right wing in the south, to the left wing and center on the Marne.
Likewise, French tactics may have been somewhat deficient, but were far from 'useless' and 'old' in 1940. The French DLMs were roughly comparable in size and composition to the German Panzer Divisions, and while the DCrs were far too 'track heavy' for 1940 (though by the standard of armoured organizations from 1942 onwards, so were the DLMs and Panzer Divisions!), the better armour and armament of French tanks gave them a tactical edge. Their smaller turrets and lack of radios were a distinct disadvantage, but in the case of turrets even the Germans only had 3 man turrets on a number of their recent Mk. III and IV Panzers, certainly not the majority compared to the Panzer IIs and 35 and 38(t)s.
Fortifications had hardly been proved 'useless' by WWI. The Liege forts imposed a significant delay on the Germans and cost them heavy losses; Maubeuge tied down a whole corps, when such forces would have greatly aided the German advance; and Forts Vaux, Souville and Fleury put up fierce resistance during the Verdun battles, while it required significant firepower and heavy casualties for the French to retake fort Douamont. The French strategy in WWII was hardly unreasonable either; the Maginot Line forced the Germans to attack through Belgium, allowing the French to economize forces, coordinate planning with Britain and Belgium, and to narrow down potential avenues of attack. That they didn't expect the Germans to risk all of their armoured and motorized forces on a crowded advance through the Ardennes also made sense; even Hitler, Halder, von Rundstedt and von Manstein thought the chances of success were quite slim. Even still, events might have played out differently had the French 7th Army not been sent to aid the Dutch, but instead remained in Champagne as Gamelin had originally planned. A better showing by the RAF and AdA against the Luftwaffe would also have improved Allied situational awareness and responsiveness. Where the Germans did meet first rate Allied forces, as opposed to the reservists that Guderian cut through along the Meuse (and even then, at places like Stonne, the outcome was far from decided), French tactics did well. At Gembloux, Hannut, Arras, and in the defensive actions along the Weygand Line and the Dunkirk Perimeter, the Germans were only able to overcome French troops with great difficulty, and Army Group C's operations against the Maginot Line tell a similar story.
Because of this, there seems to be a trend of a focus on reactionary tactics in the French Military during the time period, which I assume is related to some underlying factor in the culture of the French Military during this time period. This poses the question of what such factors were, and how they differed from Germany and England?
It should also be noted that prior to the Remilitarization of the Rhineland, French military planners favoured and offensive strategy. Belgian neutrality, British vacillation, and Germany's occupying a new border led them to turn towards a defensive strategy anchored on the Maginot Line, but the Norway Expedition, French efforts at establishing an anti-German alliance in the Balkans, and military planning against the Soviets indicate that they were coming back around to an offensive strategy prior to Fall Gelb. Similarly, while the Germans achieved great results against militarily weak foes (Poland, Yugoslavia and Greece), and against enemies caught off guard (France and the USSR) with their maneuver warfare operations, developments in anti-tank weaponry (mines, rockets, ammunition, artillery) and the ability of the Anglo-American and soviet armies to bring to bear equal or superior concentrations of force against them, meant that sweeping operations like the Channel Dash had little opportunity outside Eastern Europe. Barring surprise (Wacht am Rhein, dec. 16th, 1944) or the shattering of local enemy morale (Operation Cobra), armoured thrusts encountered great difficulty (Operations Totalize & Tractable) and required close infantry and artillery support. In this way, French tactical predictions of a 'war of fronts' came true in 1944.
Further Reading: