Admiral Raoul Castex: The Naval Strategist for Non-Hegemons
French Navy Adm. Raoul Castex (1878–1968) is the greatest naval strategist you probably never heard of. He is easily at the level of French army luminaries Marshal Ferdinand Foch (1851–1929) and Gen. André Beaufre (1902–75), as well as the two giants of modern naval strategy, the American Alfred Thayer Mahan (1840–1914) and Britain’s Julian Corbett (1854–1922). Castex’s work is vast and deep. It is rich in insights about strategy in general and for anyone concerned with seapower. Castex also offers a distinct advantage compared to Mahan and Corbett. Mahan’s work is a giant op-ed in favor of America becoming the world’s preeminent naval power; Corbett wrote from the point of view of a country that already was the world’s preeminent naval power and had been for centuries. Castex, in contrast, served a country that never was and never would be the world’s preeminent naval power. This made him far more sensitive to countries with smaller navies and offers far more of value to them as a guide to thinking about seapower, the kinds of navies they needed, and for what purpose.
Castex’s advice for smaller navies boils down to understanding how best to work with what one has, largely for the purpose of undermining the adversary navy’s confidence. He cautioned against seeking decisive battles — a priority for Mahan — and instead counseled what amounted to naval guerrilla warfare. The key for Castex was seeking always to act offensively whenever possible, and to engage in constant activity, powered by creativity, within reasonable limits.
As to why you probably have never heard of Castex, one reason is that the French navy has never had the prestige (even within France) enjoyed by its American and British peers. Few would think to turn to a 20th-century French naval theorist for guidance. After all, arguably the most useful thing the French navy did in World War II was scuttle its own fleet in Toulon to keep it out of German hands. Another reason is that Castex wrote too much. His magnum opus, Stratégies Théoriques (Theoretical Strategies), is a sprawling five-volume behemoth written and published over the course of the 1920s and 1930s. The size of the book has discouraged reprinting and translation. He has never been fully translated into English, although he has been translated into several other languages, no doubt because of his value to smaller navies. He is out of print in France, and old copies are expensive and hard to find. I had to resort to GoFundMe to pay for my 1997 set (from which all the citations below are taken). Today, the best way for readers — even French-language readers — to access Castex is through Eugenia C. Kiesling’s excellent but necessarily very abridged translation Strategic Theories.
Who Was Raoul Castex?
Raoul Castex was the son of a French army officer. He entered France’s naval academy in 1896 and quickly established a pattern: Castex graduated at the top of his class and subsequently did so in every school or training program he attended. He first served in Indochina — an experience that played a large role in his thinking, not to mention his publishing career — and repeatedly served in headquarters staffs. He spent World War I primarily focused on antisubmarine warfare and commanded a patrol vessel in the Mediterranean that hunted German U-boats. He regarded the exercise pointless — not the mission, but the manner of going about it. The experience at least prompted him to put considerable thought into submarine warfare and what submarines meant for strategy. He even wrote a separate book on the subject, published in 1920. After the war, he taught at the naval academy. In 1928, he was promoted to the rank of admiral and held several commands. In 1936, he founded France’s Institut des Hautes Études de la Défense Nationale, or Institute of Higher Studies of National Defense, which remains one of France’s premier defense institutions of higher learning. Just before World War II, Castex lost out to Adm. François Darlan in the competition to be appointed chief of the navy’s general staff, perhaps the only time in his life he did not come first.
In 1939, Castex was appointed commander of France’s northern naval forces, headquartered in Dunkirk. He made no secret of his displeasure with the disposition of French forces in northern France and feuded with Darlan, who in November 1939 removed Castex from command and forced him into the navy’s reserve cadre. Thus ended the war for Castex. Though hostile to the armistice and Vichy, he appears to have spent the war watching, writing, and publishing. He did not, as far as is known, attempt to join Free French resistance leader Charles De Gaulle in London or the commanders who rallied in North Africa. He kept to his writing and attended conferences into the 1950s until finally he slowed down and passed from the scene.
Castex’s Theory on the Purpose of Navies
Mahan, the grandfather of modern naval strategy, articulated two arguments that largely have been taken as axiomatic by naval theorists ever since: First, seapower is critical for any country with global ambitions, and second, the fundamental reason for navies to exist and thus the objective around which they should be designed and operate is to destroy the adversary’s navy on the high seas, ideally in a decisive fleet action. In Théories Stratégiques, Castex agreed with the first argument. As for the second, Castex introduced an important measure of nuance. Yes, operating on the high seas and destroying the enemy’s fleets should be one’s primary objective: “Everything, or almost everything, against the enemy fleet. Nothing, or almost nothing, for the rest.”
However, over the course of hundreds of pages, Castex introduced caveats and exceptions. For smaller navies, this is crucial: ocean-going fleets capable of challenging other fleets and destroying them in decisive battles might well be beyond the means of many.
Similarly, Castex argued that sea control or command of the sea, however desirable an ambition, was always at best relative even for the most powerful navies. Fleets may control the waters where and when they are present, but then they move on. Besides, submarines exist. “If I have ten submarines and my adversary 50,” he wrote, “he does not have mastery, for his submarines in no way prevent mine from circulating in the water.” The implication was that command of the sea was not really the end-all, be-all of naval strategy. Again, this gives weaker navies a break: He’s signaling that they need not fret about their inability to impose sea control.
Castex understood that destroying the enemy’s fleet often is easier said than done, especially but not exclusively for weaker navies. One’s own fleets are finite. The resources required to build and maintain fleets are finite. The sea is vast. The enemy may well have more ships. The number of tasks to which one’s naval forces must attend (i.e., blockading, counter-blockading, attacking and defending commercial shipping, landing and supply ground forces, etc.) are numerous. Navies do not enjoy the freedom to do entirely as they please and to pursue without distraction a purely naval strategy. Sometimes they could not because of their inferiority relative to enemy navies. More universally, there are other demands on navies’ resources. So, how does one prioritize?
Maneuver as Art
Maneuver probably was the idea most dear to Castex. He defined it as “moving intelligently to create a favorable situation.” This definition, Castex insisted, applies to “all forms of human activity in which it is a question of struggling, of obtaining a goal by surmounting obstacles.” The idea is to take the initiative to “modify or determine the course of events, to dominate destiny and not to abandon oneself to it, to engender and give birth to facts.” Indeed, “one does not conduct a maneuver by being subject to the will of the enemy and by accepting the law of luck.” Interestingly, he insisted that maneuver does not necessarily mean physical movement. It could just be an intellectual shift, a different way of thinking about problems.
Because of its creative element, maneuver was, for Castex, a “work of art.” It was a “product of intelligence and imagination that guide technique without ignoring one’s possibilities and one’s limits.” Great military maneuvers, therefore, were akin to great works of art. “Before certain maneuvers,” he enthused, “whether it is a question of the work of a Suffren, a Ruyter, a Nelson, a Napoleon, a Schlieffen, or a Foch, one experiences the same emotion as in front of true works of art, such as before a painting of Rembrandt, or before Notre Dame.”
Castex understood all the reasons why navies and other military branches could not readily pursue their primary objectives, especially given their many servitudes, a term he used to refer to obligations outside of naval strategy to which navies had to attend, such as policy, the need to support land strategy by helping to sustain or move troops, or to defend coasts because the public demanded it. The idea, however, was in all things and at all times to have a maneuverist outlook.
The Primacy of the Offensive
Aligned with Castex’s views on maneuver was his faith in the virtues of the offensive. “The offensive represents action and movement,” he wrote. “It transforms the power relationship. It modifies situations. It changes a stage of things to another that it seeks to realize. It engenders the novelty it conceives. It obliges birth. The offensive is, par excellence, a creative act.”
The defensive, in contrast, “can only be static.” At best, it prevents the adversary from succeeding in its creative act. It is “an act of sterilization vis-à-vis the germs of life that tend toward the evolution of a crisis; it is an effort of non-transformation. … The offensive imposes, the defensive suffers.” Of course, sometimes the defensive is necessary, but war, he argued, requires positive goals that only the offensive can achieve.
As with all “principles,” Castex warned against being too dogmatic. There were no absolute rules, he insisted. One must think first, and see if certain conditions are met. First, one must have the means in quantity and quality. Numbers count, as well as the quality of one’s ships and their crews. “One must tend constantly toward the offensive […] but at the same time one must know that one does not go on the offensive as one wants, and when one wants, blindly, all the time and in all places.” Sometimes, it is best to wait. And sometimes, one must go on the defensive. After all, economy of means obliges one to be on the defensive somewhere. Realism must have the upper hand. Castex concluded that “the plan of maneuver must tend toward the realization of the idea the most offensive and positive that one reasonably can conceive.”
Advice for Smaller Naval Power
Castex’s arguments in favor of realism and being as aggressive as one can given one’s means are part of what makes his work valuable for weaker navies. He did not urge them to sail out onto the high seas determined to force a decisive battle against the enemy’s fleet. He thought smaller navies could and should play a smarter game, one that was within their reach in terms of their resources, yet still worthwhile, strategically speaking.
Castex counseled weaker navies to avoid decisive battle. What they could do, assuming they maintained their offensive and maneuverist spirit, was seek to keep sea control in dispute as long as possible, and also to strive to force the enemy to disperse its fleet or immobilize some of its assets. Isolated ships could be defeated even if fleets could not, and sooner or later, forcing the enemy to disperse would create opportunities that one might seize. Sometimes, one had to lay low. Sometimes, one had to seek refuge. But “movement is the law,” and it was critical to return to the open sea as soon as possible. The commander of a weaker force must be creative, and the less encumbered by servitudes, the better. This means, among other things, disregarding public opinion, which might pressure commanders to do things contrary to their good sense.
Castex’s main recommendation for weaker navies was the concept of “minor counter-offensives,” a term for which Castex credited Corbett. The idea is to disrupt “the game” of the enemy. They should be limited and not overly ambitious. They might consist of attacking enemy communications, which can involve commerce raiding. Commerce raiding can be strategically useful, Castex explained, provided it is part of an overall strategy and not pursued as an end to itself. Castex was convinced that submarines and aircraft were ideal for “minor counter-offensives.”
According to Castex, undertaking “minor counter-offensives” is good for morale. If one stays inactive for too long, passivity sets in, and one is not prepared to take advantage of opportunities to go on the offensive as they arise. Activity, for Castex, has a virtue all its own, and he stressed that weaker navies benefit more from it than stronger ones. Among other things, he wrote, it can foster doubt on the part of the stronger navy about its presumed superiority. Elsewhere, Castex described naval operations in ways that today might be described as “psychological operations.” The threat one can pose to the adversary’s fleet might be more important than any real damage done to it. The goal is to worry the enemy and, ideally, make it disperse. Castex went so far as to imagine a naval guerrilla war, which might consist of raids, bombardments, and coups de main. Secrecy, speed, and surprise were essential; the weaker commander had to carefully select the right opportunity and strive to ensure his force’s dominance at a chosen time and place.
Lessons for Today
Castex echoed Mahan in his emphasis on fleet action and the idea that a navy’s primary objective should be to defeat the adversary’s. However, he was impressed by the need for navies to attend to other tasks (the servitudes), as well as the fact that often navies were not able to risk fleet action or decisive battle of any sort. Better that they should strive to preserve their fleets, so long as they did not slip into passivity. Naval commanders had always to be alert and active, looking for opportunities, seizing them, and, whenever possible, creating them. Thus, maneuver —“moving intelligently to create a favorable situation” — was everything. This approach arguably makes Castex a more useful resource for smaller navies today than Corbett and Mahan, who either wrote from the point of view of a naval hegemon or aspired to become one.
Smaller navies needed to think in terms of fostering uncertainty on the part of more dominant navies regarding their control of the sea. Submarines were profoundly useful in this regard, as were aircraft and other means of striking ships at sea. No doubt Castex would have approved of Ukraine’s use of drones to neutralize the Russian Black Sea fleet, or the Houthis’ use of drones and missiles to challenge even the U.S. Navy’s control over the Red Sea. Mines, too, he approved of. Castex probably would have disapproved of Argentina’s failure to use submarines or mines to complicate the Royal Navy’s efforts in the Falklands war, especially given Britain’s adept use of submarines to scare away Argentina’s powerful surface fleet. Argentina at least used airpower well, but that proved insufficient. Argentina could have found ways to threaten Britain’s long lines of communication. Again, submarines would have done the trick. Similarly, if the war were to take place today, drones and missiles might have made all the difference. These are the ultimate weapons of the weak, and their proliferation both empowers weaker countries and gives stronger ones real reason to be concerned.
Do the new weapons require changing one’s approach to naval strategy? Castex was hostile to the Jeune École and the “materialist” school of naval theory it represented. The materialist school argued that technological changes rendered age-old principles of war irrelevant. Thus, the Jeune École in the late 19th century argued that France should abstain from the race to build massive capital ships capable of decisive fleet actions and instead build large numbers of fast, smaller vessels armed with what at the time were the new high-tech weapons of the day: torpedoes. Castex rallied to the “historical” school associated with Mahan and Corbett. Nonetheless, he believed that militaries had to adapt and learn to apply the venerable principles of war in light of modern technology. At one point, pondering the advent of submarines and naval aviation, he even suggested that maybe the Jeune École had a point at least with regard to the threat to large and expensive vessels that were increasingly vulnerable. The problem with the Jeune École was that the ships it inspired were incapable of operating on the high seas, and incapable of challenging enemies’ surface fleets, which needed to remain, despite everything, navies’ primary function. Castex was interested in finding some sort of compromise. At the very least, he was enthusiastic about submarines’ potential. He would almost certainly have approved of the AUKUS partnership. Nuclear-powered submarines, which came into existence toward the end of his life, would have given him joy.
Michael Shurkin is the Director of Global Programs at 14 North Strategies and is an Associate Fellow at the Royal United Services Institute (RUSI). He was a senior political scientist at the RAND Corporation and a political analyst in the CIA. He has a Ph.D. in Modern European History from Yale University.
