Armies generally say that “geography is destiny,” because their concentrated forces cannot move effectively without the right terrain. Often terrain dictates what an enemy can do. The sea presents far less in the way of determining terrain, and more freedom of action. The sea is vast and trackless, but even so, geography, largely at its edges, shapes what navies can do.1
The most obvious naval impact of geography is the way in which it limits how a navy can reach the open sea. Even now, with all sorts of ocean surveillance, the best way to block or strike an adversary navy is to await it in a strait through which it must pass to get to the open ocean. Missiles backed by long-range radar can complicate passage of even a wide strait.
The existence of islands close to a potentially hostile shore offers an opportunity for naval forces to change the balance of naval geography. The Chinese see the First Island Chain, which extends from Japan south through the Ryukus, Taiwan, and the Philippines to the Strait of Malacca, as needing to be dominated to ensure their security. They see these islands forming barriers to enemy naval forces coming at China, but also as hemming Chinese forces inside the East and South China Seas. History suggests there is enough sea between the islands to make such a claim questionable. On the other hand, to get into the open Pacific the People’s Liberation Army Navy (PLAN) would have to pass through the same chains.
To create forward defenses, China has built and fortified a number of small island bases in the South China Sea. However, the loss of one or more of these islands, say to U.S. Marines early in a war, would probably compel China to try to get it back. In the process, the PLAN might lose a valuable part of its fleet. In such a fight, the Chinese would face the usual disadvantages of land forces facing seaborne ones. The seaborne force (U.S. Navy and Marines) would get to choose its targets, and those choices could be made difficult to predict. The defender must prepare against all possible attacks, tying down larger forces.
China’s problem is similar to the choice Japan faced as the U.S. fleet advanced across the central Pacific during World War II. The Japanese could never be sure where the U.S. Navy would strike, and its overall resources were limited. The Japanese fleet could not possibly reach all potential targets quickly enough, so it opted for a defense by shuttling aircraft along the island chains it controlled. It turned out that U.S. attackers could beat off Japanese attacks in detail; and the Japanese could never concentrate enough aircraft to deal with the U.S. carrier force that overran their islands.
Today, China’s bases are a lot closer to the island chains it wants to control, at least the ones right off its coast; but it also has many threats to consider in a war. To what extent are long-range antiship missiles a viable substitute for aircraft, ships, and troops? That depends on how good China’s ocean surveillance is, and on how well it can determine where U.S. naval forces are going and how well they can deal with missile attacks. One missile may be enough to neutralize or sink a ship, but it is not enough to neutralize a dispersed force of Marines on an island—as Russia has been learning in Ukraine.
History shows how important maritime geography has been. For example, for centuries an important reason for British naval dominance was that the British Isles were, in effect, a stopper in the North Sea. A ship from Continental Europe trying to reach the open Atlantic had to go either north of Scotland or south through the Channel. British fleets operating around those two bottlenecks could almost inevitably block surface fleets. In 1941, when the German battleship Bismarck steamed toward the Atlantic, the British could be sure of intercepting her as she transited the Greenland-Iceland-UK gap. They did so, but she sank HMS Hood and broke out into the Atlantic. Geography made that break-out potentially disastrous, because there were no onward constraints to determine where the battleship might go. Fortunately, the German battleship was damaged, and her commander felt constrained to get to St. Nazaire, France, the only place on the European Atlantic coast that had a drydock large enough for Bismarck. She was caught en route.
The British also had to be concerned with the Mediterranean. That is why Gibraltar, the choke point at its mouth, was always so important to them. Gibraltar was particularly important because both main British naval enemies of the 18th and 19th centuries—France and Spain—had Atlantic and Mediterranean coasts. They had to split their fleets, and the Strait of Gibraltar lay in the way of any attempt to join the two fleets together for maximum effect.
Of course, geography is not fixed. An army can change naval geography by seizing land that impacts naval operations. In 1940, the Germans suddenly gained control of the coast of Western Europe and placed U-boats on the shores of Norway and France, bringing them closer to the open Atlantic. From those locations, they could spend more patrol time where their targets were. Years later, during the Cold War, the U.S. Navy recognized that naval geography could offer important advantages, and that a hostile army could wipe them out—as the Germans had in 1940. The U.S. Navy recognized that it had a vital interest in preserving favorable naval geography in northern Europe, and it promoted efforts in that direction.
The fewer the determining choke points, the more a navy has to rely on ocean surveillance to find its enemy. The Pacific presents no obvious choke points to the east of Japan. The interwar U.S. Navy, which was designed with a possible Pacific war in mind, had to work hard to detect and track any possible Japanese fleet sortie. That led to developments such as the fleet submarine and intense work on code breaking. The Japanese had a similar problem. Between World Wars I and II, U.S. wargamers assumed that in a crisis the Japanese would surround the U.S. fleet base at Pearl Harbor with submarines, not to attack, but for the important task of determining where the U.S. fleet was headed. To make this point, one year the game supervisors allowed the U.S. fleet to get out of Pearl Harbor without being tracked (the Japanese submarines were successfully held down by depth-charging). The result was instructive: for several weeks, the Japanese commander panicked as his scouts failed. Of course, this is not 1934, and ships at sea are a lot easier to find. However, even now ocean surveillance becomes more difficult as the target gains freedom of action.2
Bases are an important aspect of naval geography. Although ships have long ranges, how much they can do depends heavily on logistics. Again, the experience of interwar gaming is instructive. The great problem for wargamers was how to deal with a Japanese attack on the Philippines, then a U.S. possession. Strategists realized that the object of the war would have to be Japan itself, and that the appropriate endgame was strangulation. That required controlling the requisite geography. Under the international rules as then understood, blockade required that merchant ships be visited to determine whether they were carrying contraband. That in turn meant that a blockader had to use large numbers of ships.3 U.S. strategists saw successfully seizing islands near Japan as a precondition, with the islands supporting the blockaders. There was some question as to whether the Japanese would surrender in the face of a tight blockade. The Army Air Corps advocated burning the country down as an alternative. The same islands that would make blockade possible would also support a bombing offensive.
The prerequisite for any of this was to destroy the main Japanese fleet, which served as the shield of Japan. The U.S. Navy initially concentrated on that task, as did the Japanese, who expected to fight a decisive battle near Japan. For years U.S. naval strategists assumed that, on the outbreak of war, the fleet would head directly for the Philippines, a strategy called the “Through ticket to Manila.”4 The decisive battle would be fought either en route or after the fleet arrived.
Naval geography was relevant. After World War I, Japan had been granted mandates over island chains lying between Pearl Harbor and Japan. It was assumed it would base aircraft on them; the U.S. fleet would have to beat them off. One consequence was that U.S. carrier aircraft were designed to fight the best land-based aircraft.5
The Naval War College held a month-long wargame every year to simulate a large part of the Pacific war the Navy was being designed to fight. It generally included a big battle with the Japanese fleet. In 1933, the War College’s Captain Wilbur van Auken was assigned to draw lessons from the war games. At first glance that year, as usual, the U.S. fleet emerged more intact than the Japanese. Van Auken, however, pointed out that this apparent success had to be evaluated in view of geography. The U.S. fleet actually suffered serious underwater damage, and geography denied them any repair facilities west of (distant) Pearl Harbor, particularly if (as expected) the Japanese had already seized the one U.S. Navy yard in the area, at Cavite near Manila. The Japanese had no such problem. Within a short time, the surviving Japanese ships would be repaired while U.S. ships would be lying on the bottoms of Philippine bays to which they had steamed.
The War College president considered this result so important that he sent material on the game to the Chief of Naval Operations, who ordered the war plan recast. To fight far beyond Pearl Harbor, the Navy had to exploit geography in chains of islands and atolls to create forward bases capable of repairing battle damage and supplying the fleet. The Navy created a vast mobile base structure that could move as needed.
The mobile logistics machine was not enough, however. It worked because the Navy conquered places where it could be based, most notably Ulithi Atoll, in the Caroline Islands, with its vast natural harbor.
The other part of the strategy recognized that the fleet had to deal with the Japanese forces defending the islands. It was still valid to think of the islands as mutually supporting air bases. The U.S. counter was to seize islands and use them as air bases to strike further Japanese islands, helping the fleet advance. Whatever cooperation the Japanese expected to achieve between garrisons on different islands had to be broken. Using naval geography this way exploited the inherent mobility of naval forces. The Japanese could never be sure where the Americans would strike; naval mobility gave the U.S. Navy far too many choices. For example, in the spring of 1944, the Japanese naval staff drew up a plan for the next phase of the war. To deal with uncertainty, it included numerous alternatives to handle U.S. attacks on varied possible targets (the U.S. Navy obtained a copy of the plan shortly thereafter).
Historians often write that the Japanese were motivated to attack Midway because they wanted to cement a barrier against U.S. attack. If that was their idea, the successful U.S. carrier raid on Tokyo in April 1942 should have disproved it.
Rather, the Japanese naval strategists recognized another reality of naval geography and strat- egy. Unlike ground forces, naval forces are very mobile but also limited in numbers. The object is to achieve naval dominance by damaging the enemy navy so badly that it cannot recover. By attacking what seemed to be a vital U.S. interest at Midway, the Japanese hoped to lure the U.S. fleet into a fatal decisive battle.6 Destroying the U.S. fleet would have freed the Japanese to do as they wanted, at least until the United States could rebuild.
An important current question about naval geography is whether masses of long-range land-based missiles and bombers coupled with ocean surveillance systems have changed the character of naval warfare sufficiently that they can cover broad ocean areas. Is the vastness of the oceans still a crucial fact of naval geography?
If fleets are still the dominant fact of naval strategy, then naval logistics is still key for all involved. Logistics is a chain extending from a home country to a deployed fleet; the strength of the chain determines the fleet’s mobility. One end of the chain is underway replenishment ships. Their cargoes must come from a supply source. Typically, a base is needed as an intermediate point at which the supply can be built up, beyond what replenishment ships can carry. Bases are also essential for maintenance and battle damage repair.
Right now, China has no bases in the central Pacific. The United States has bases all over the Far East, which means its military possesses elements of naval geography that would make it possible to sustain operations near China. China does not currently have any equivalent in the central or eastern Pacific, but it is building political ties that will allow it to develop a base structure. Current developments in the Solomons are the most prominent case.7
Just how the size of the ocean affects conflict depends on where a war is fought. The closer to shore, the less the scale of the ocean may count. An attacker coming from offshore can magnify the problems of the defender by increasing striking range, i.e., enlarging the area of ocean from which he can strike. That is one reason the U.S. Pacific Fleet late in the Cold War practiced long-range air strikes against the Soviet Far East. Enlarging the area from which it could strike greatly complicated the Soviet defensive problem. The Soviets tried to overcome this problem by improving their own ocean surveillance system.
Bases have another important aspect. As in the 1933 war game, ships do not have to be sunk to be rendered combat ineffective if damage cannot be repaired in a forward area. To be able to project power effectively and continually inside the First Island Chain, the U.S. Navy would have to overcome that fact, much as it did in World War II. Fighting near its own coast, the PLAN would benefit from short logistics chains, well-developed naval industry (if adapted to repair as well as to new construction), and land-based aircraft and missiles. The farther from home the PLAN has to fight, the more it would need bases and logistics linked back to its industrial base at home. Those bases and logistics chains would be both strengths and vulnerabilities.
- Apart from underwater geography, which determines how sonar works and where submarines can operate.
- It may seem that the proliferation of satellites will end the sea sanctuary altogether. However, imagery satellites produce images of limited areas. The ocean is so vast that it cannot be covered in this way alone. Electronic intelligence (ELINT) satellites detecting ships’ emissions are another story. Recently there has been considerable discussion of satellite systems that track Russian oil tankers based on their AIS signals and the detailed character of their navigational radar emissions (a technique called Specific Emitter Identification in its naval form). Such techniques are vulnerable to spoofing, which may be an important future function of unmanned surface and subsurface craft.
- For a summary of interwar plan development, see this author’s Winning a Future War (Washington: Naval History and Heritage Command, 2019). It describes the intertwined history of Naval War College gaming and war planning, the former often driving the latter. The OpNav War Plans Division used the annual War College games as its laboratory. Attendance at the Naval War College was a prerequisite for assignment to the War Plans Division. For many years the then–Naval Historical Center had microfilms of the 1929 Orange War Plan documents, including the discussion of what to do if the Japanese failed to give up after being strangled. Actual invasion of Japan was rejected on the ground that the United States could not possibly create an army of the requisite size. The microfilm collection included analyses of U.S. merchant ships suitable for various wartime tasks, including using transport ships, used to bring army bombers to theater, to the blockade islands off Japan.
- LtCol Richard Beil, USMC (Ret.), “Island Hopping in World War II—Trench Warfare at Sea,” Military History Online, 10 June 2019.
- U.S. naval fighters did not quite match land-based aircraft until the advent of aircraft with engines in the 2,000-horsepower class in 1942–43 (the Hellcat and Corsair), but the previous generation (Wildcat, and to an extent the Buffalo) were competitive with many land-based airplanes, as the Finns showed in 1939–40 when they flew Buffaloes against the Soviets. With the right tactics, Wildcats competed effectively against Japanese Zeros, which in turn was effective against contemporary land-based fighters. For details, see this author’s Fighters Over the Fleet (Annapolis, MD: U.S. Naval Institute, 2016).
- Probably the best account of Japanese thinking leading up to the battle is Jonathan Parshall and Anthony Tully, Shattered Sword: The Untold Story of the Battle of Midway (Washington, DC: Potomac Books, 2007). The Americans could not fail to defend Midway because it is the westernmost island of the Hawaiian chain. A Japanese air base there could have been used to bombard Pearl Harbor, the main U.S. naval base west of the big fleet base at San Diego.
- Jonah Blank, “China’s Troubling New Military Strategy Is Coming into View,” The Atlantic, 5 May 2022.