Essays & Reviews

Mahan, Choke Points, and the Panama Canal

The recent blockage of the Suez Canal by the container ship Ever Given is a reminder of the importance of maritime choke points as they concern international commerce and national security. Choke points are primarily the effect of natural geography, which is one of the critical dimensions of strategy. (For a review of notable Classic understandings of geography, see this CSD essay by Christopher Flannery ). 

In some cases, however, human agency, especially technology, can affect the strategic importance of natural geographic features and relationships. The shift from sail to steam, then from coal to oil-fired ships. From roads to railways. From horses to internal combustion engines. From the ground to the skies — aircraft to ballistic missiles, to drones, and hypersonic vehicles. 

Another human agency is the construction of canals in a way that significantly alters the geopolitical terrain. Two canals come immediately to mind: Suez and Panama (one might add the Kiel Canal, given its effect on the British-German naval balance in the early part of the twentieth century). Canals not only facilitate maritime traffic but, by their nature, become choke points. They are subject to disruption or closure by accident, sabotage, or outright military action. The grounding of the Ever Given delayed over 350 ships, thereby disrupting the tightly knit global supply chain for weeks, perhaps months. Some vessels diverted to the old route around Africa, adding time to the passage and the risk of piracy along the east African coast. In an emergency, the blockage could seriously compromise a rapid shift of U.S. military assets from the Mediterranean to the Persian Gulf/Indian Ocean (or vice versa).  

With reference to the strategic Classics: one of our Scholar alums, Joshua Boucher (now faculty at Holy Cross) considered specifically Alfred Mayer Mahan’s The Interest of America in Sea Power, Present and Future (1897). In this and other publications, Mahan ruminated deeply on what he regarded as the requirements and risks created by a future choke point, a Central American canal. The construction of such a canal had been discussed for decades but at the turn of the century it finally seemed technologically and politically feasible. A French firm led by the man who had been in charge of the Suez Canal project tried and failed, but someone was bound to do it. Mahan believed the cutting of a canal in Central America would make the Caribbean assume an international importance it had not held since the days of Columbus. 

A Central American canal also meant the Pacific shore of the United States would naturally grow in importance because of ease of access. With the increase of population and wealth on the west coast, and growing trans-pacific trade, the United States would become a true transcontinental power. As a consequence, America would have to protect two ocean coasts, the Gulf of Mexico, and its Pacific trade. According to Mahan, Europeans previously uninterested in the Pacific coast might suddenly be interested when they could reach it so easily through a canal. With easy access to the Pacific, and with increased amounts of sea traffic along all the shorelines of America, Mahan stressed the importance of American control of the canal and, essentially, the whole Caribbean region—especially because the isthmus would take on international commercial and military interest on a scale never previously possessed.  

In the “Isthmus and Sea Power,” from the September 1893 issue of the Atlantic Monthly, Mahan pointed out that control of the canal depended upon sea power. Control of the isthmus was possible only through naval control of the region, and naval control of the region required naval predominance. Naval predominance could not be obtained unless Washington was serious about upgrading its naval material and personnel. “The United States has asserted a special interest” in the Isthmus, Mahan wrote, and “in the present she can maintain her claim, and in the future perform her duty, only by the creation of that sea power upon which predominance in the Caribbean must ever depend.” 

Without the canal, the United States could ignore its naval prerogative in the Caribbean. But as soon as the Europeans, now in the process of a massive and competitive colonial expansion, showed interest in the area, Washington could not appear weak. British control of the canal might be acceptable. Unlike many Americans, including Theodore Roosevelt and Henry Cabot Lodge, Mahan believed Anglo-American cooperation to be generally desirable, but the United States could not count on such a favorable, low-cost occurrence. Control of the canal, in the wrong hands, would be a disaster for the United States. A hostile power could move its naval forces from one ocean to another with impunity. At the very least, it could close the canal, preventing the United States from rapidly doing the same with its fleet and choking off its commerce. The only way fully to avert disaster was to take control of the canal, and have the means to defend it and keep it open for American purposes.  

Even for those Americans who wanted to remain isolated in the world, the creation of the canal would forcibly end it: This isolation will pass away, and with it the indifference of foreign nations. From wheresoever they come and whithersoever they afterward go, all ships that use the canal will pass through the Caribbean.”  

The other closely related location of critical strategic importance for Mahan was Hawaii. (See for example “Hawaii and Our Future Sea Power,” in the Forum, March 1893).  Mahan argued that the military value of a naval position depends upon its situation (location), strength, and resources, with situation being the most important factor. Hawaii possessed one of the best situations in the entire Pacific, he argued, “equidistant from San Francisco, Samoa, and the Marquesas, and an important post on our lines of communication with both Australia and China.” Its situation fulfilled Mahan’s dictate that no foreign power control important points within 3000 miles of San Francisco. Moreover, its situation also related to control of the new Central American canal—any power looking to pass to China or Japan through the canal would have to go by Hawaii; therefore, possession of Hawaii reinforced American control of the Caribbean and Canal. By pushing for control of Hawaii, Mahan had two objectives: (1) a foothold for control of the Pacific, and (2) a reinforcement of American control of the Caribbean and the Central American canal.

Mahan’s final word on the subject came shortly before his death (“The Panama Canal and the Distribution of the Fleet,” The North American Review, September 1914). Written just before the outbreak of World War I, Mahan stressed one of his major lifetime themes, the absolute necessity to concentrate the fleet in combat. But how could this be done given the need to protect two coasts and interests in both oceans without the inordinate costs of building two separate and superior fleets? 

The answer, he reiterated, was the Panama Canal, which had just come into operation. It allowed the United States to swing the navy from one ocean to the other, according to emerging threats and opportunities. It was highly unlikely that a Pacific and Atlantic enemy could coordinate and operate effectively to pose simultaneous threats to each coast. But in the worst-case scenario, if properly fortified, the Canal afforded a retreat in case of reverse, and a means of speedy return when reestablished. “The Canal, in short, is a central position, from which action may be taken in either direction, and it is also a decisive link in a most important line of communications.”

But all this was contingent on the security of the canal and why it must be fortified and kept open. “An enemy by occupying it in force would acquire advantage for keeping apart the divisions in the two oceans, if not already united. . . an artificial channel, with locks, in a region like Panama, stands always in risk of interruption. Accident, surprise, treachery, a momentary lack of vigilance, other fortune of war, may effect a prolonged block of an essential line of communication, affording an enemy a strategic opportunity, through possessing decisive local superiority for whatever the period of closure may be.”