Major General Charles Callwell—the Forgotten Maritime Strategist

Ask any naval history aficionado to list the most influential maritime strategic thinkers and U.S. naval officer Alfred Thayer Mahan and British writer Sir Julian Corbett invariably appear. This is hardly surprising as these two late 19th-/early 20th-century scribes are considered the doyens of the field of maritime strategy. 

Mention Major General Charles Callwell, however, and expect puzzled looks from all but the most learned naval historians. Prima facie, one invariably would think: “How much could an army man know about saltwater affairs?” As a contemporary of Mahan and Corbett, Callwell is noted more for the seminal Small Wars: Their Principles and Practice, a book that deals with irregular warfare and is considered required reading for the modern counterinsurgency practitioner. 

What is much less known about Callwell is that he also wrote extensively on the land power–sea power nexus and is one of the few to have pointed out that ground forces can contribute to maritime strategy. Indeed, most thinkers, especially Corbett, dwell on the reverse of this relationship—how navies can shape events ashore. With maritime competition ratcheting up among the great powers, Callwell’s ideas are worth revisiting. Should he be alive today, what would he say about the influence of land forces on maritime affairs in the contemporary era? 

The Sea Power from Land Power Thesis

Writing in Military Operations and Maritime Preponderance: Their Relations and Interdependence (1905), Callwell asserts, “In some situations the influence over the course of naval warfare exerted by land operations, and by the expenditure of purely military force, may be almost imperceptible; in others it may be paramount.”¹ All in all, he says, “ Its possibilities can never be wholly left out of account in framing a plan of maritime campaign.”² In other words, land forces can shape affairs at sea, at least to a certain extent. 

To substantiate his argument, Callwell cites various examples, such as the Napoleonic Wars and the Russo-Japanese War, where armies seized enemy naval bases and contributed to the maritime outcomes of these conflicts. Hence, he concludes, “Naval warfare is not a war of posts. But its true object, the breaking of the enemy’s power at sea, cannot be achieved without posts.”³ He also says “it is in the ‘war of posts’ that the dependence of sea-power upon land-power asserts itself, and that military force comes to the aid of naval force.”⁴

Events in more modern times also have borne out Callwell’s thesis. During World War II, the fall of France drastically improved the maritime geography of the Nazi imperium. Prior to the capitulation of Paris, Germany’s maritime geography was such that U-boats had to run the gauntlet of the British antisubmarine dragnet in the North Sea to reach the Atlantic Ocean. France’s defeat meant German submarines had points d’appui in the Bay of Biscay and direct access to the Atlantic—with initial deleterious consequences for the Allies. On the Eastern Front, Germany’s capture of key Soviet naval bases in the Black and Baltic seas hamstrung Moscow’s war effort. Similarly, as the Red Army marched westward in 1943, taking vital maritime territory along the way, the fortunes of the Soviet Navy improved significantly.

21st-Century Callwell

If Callwell were to comment on today’s land power–sea power nexus, he likely would stress the importance of ground forces in advancing sea control, but with some nuances to account for the profound changes in the politico-military environment in the past century. Indeed, the aforementioned examples of land power abetting sea power took place before the advent of the long-range precision-guided missile. 

A 21st-century Callwell no doubt would incorporate this game-changing weapon into his ideas. For one, he likely would praise China’s strategy of “using the land to control the sea,” where shore-based antiship missiles (ASMs) of the People’s Liberation Army (PLA), such as the intermediate-range DF-21D or DF-26 “carrier killers,” could hold at risk enemy naval forces during a crisis. In fact, there is much talk of such weapon systems deterring the U.S. Navy’s approach to the first island chain during a Sino-American clash. 

That being said, Callwell probably also would note with interest China’s “fortress fleet” concept, where the PLA Navy could operate safely within the first island chain littoral confident that Chinese rocketeers could keep opposing forces at bay.⁵ In Military Operations, Callwell notes “the principle that fighting-fleets must gain their victories at sea, and cannot under the normal conditions of a maritime struggle destroy the naval forces of the enemy when these take shelter under the wing of fixed defences.”⁶ Here, Callwell is adhering to Admiral Horatio Nelson’s maxim that “a ship’s a fool to fight a fort.” 

At first glance, advances in defense technology (especially long-range, land-based ASMs) in the centuries since Nelson’s day have seemingly only strengthened the validity of that notion. But a closer look shows that the statement can be challenged today. Callwell no doubt would factor in, inter alia, the striking reach of air power as well as the greater mobility, stealth, and amphibious competence of modern navies. He would temper his original point of the unfeasibility of navies squaring off against shore defenses, noting that the attributes of modern naval forces mean they could attack a “fort” via its rear rather than head on.⁷

Callwell also would nod at the recent discourse on having missile-armed U.S. ground forces play a larger part in the quest for sea control in the western Pacific. He likely would approve of the “archipelagic defense” concept where forces in bases within the first island chain, such as on the Ryukyus, would turn the antiaccess/area-denial table on the Chinese.⁸ He also would approve of the U.S. Marine expeditionary advanced-base operations (EABO) concept, which is similar in several aspects to archipelagic defense and calls for the seizure of forward bases, consistent with Callwell’s ideas.⁹ While the “posts” that Callwell stresses should be seized refer to naval bases and “maritime fortresses,” should he be around today, he would find that the fires and supporting nodes called for in joint operational concepts such as EABO and the U.S. Army’s multidomain operations belong in the same category. 

Going Forward

Strategic affairs commentator Robert Kaplan once said, “Never provide your adversary with only a few problems to solve . . . because if you do, he’ll solve them.”¹⁰ He makes this point in a commentary on dealing with China’s rising military prowess. With the current emphasis on cross-domain synergy to complicate the adversary’s planning, it is fitting that the United States is leveraging traditional non-naval services such as land forces in its sea-control calculus. 

In this regard, Charles Callwell’s ideas on the influence of land power on maritime affairs are still relevant today. He also writes of “evils which arise when military and naval forces, intended to act in co-operation, fail to do so from want of mutual understanding.”¹¹ Put in simpler terms, Callwell recommends greater jointness between the army and navy (and the air force had it existed during his time). While this is an ad nauseam point, it is surprising how armed forces have often overlooked it. Perhaps it is time that defense planners in the highly maritime Indo-Pacific region pay greater attention to Callwell’s Military Operations and Maritime Preponderance and adapt its pertinent points to suit the 21st-century strategic environment.