both permanent and temporary, formed an important element of American military activity as early as the colonial period and remained a highly visible aspect of national defense well into the twentieth century.
A major threat facing isolated coastal communities in colonial times was seaborne attack by European forces. The defensive works built by the colonists were mainly small, primitive attempts to replicate the European bastion‐trace fortification with its prominent corner gun platforms. Most were constructed at the water's edge of port cities, using whatever local materials were available. The American Revolution triggered a revival of local construction, but with little change in either materials or design. Most fortifications built during the Revolutionary War itself were field fortifications rather than permanent works. Classed as either complex entrenchments (with small, reinforced earthen and timber works often connected by ditches to serve as trenches) or hasty entrenchments (the normal ground configuration supplemented by minimal construction), fieldworks also followed European models. Having no indigenous military engineers, the Continental army relied mainly on French‐trained officers, such as Louis La Bèque Duportail and Thaddeus Kosciuszko, for the expertise needed to construct larger works in the field—a tradition that would continue into the nineteenth century.
The emergence of a plausible threat in the 1790s during the French Revolution led to the first of two “systems” of coastal fortifications prior to the War of 1812. The “First System” of 1794 was the initial effort undertaken by the federal government, and it represented a continuation of past practices both in terms of design and materials and in reliance on European engineers (one of whom was Pierre L’Enfant, the future designer of Washington, D.C.). The “Second System” emerged in 1807, also in response to a foreign threat, this time from Britain in the Napoleonic Wars. This system included works built to a novel design advocated by Jonathan Williams, first U.S.‐born chief of the U.S. Army Corps of Engineers. He endorsed the construction of works with high stone or brick walls, the guns arranged in multilevel tiers of internal chambers called casemates, and firing done through iron‐shuttered embrasures piercing the facade. This theory, based on the ideas of a French engineer, the marquis de Montalembert, meant two or three tiers, and thus more guns and greater defensive firepower within the same ground occupied by an older‐style, single‐level fortification.
A handful of American fortifications designed to Williams's ideas, including Castle Williams in New York Harbor, arose before 1812; but the impact of these ideas was far greater in following decades. During the War of 1812, British coastal raids—and the burning of the national capital—persuaded national leaders to establish a board of engineers in 1816 to examine the entire coast and recommend defenses. The Bernard Board Report of 1821, named after French engineer Simon Bernard, was the first comprehensive plan for American coastal defense. It led to construction of the “Third System” of some fifty American coastal forts, almost all of them casemated works built to designs of increasing sophistication.
The leading figure of this program was Joseph G. Totten, an 1805 graduate of West Point and later chief engineer of the U.S. Army 1838–64, the longest tenure of any chief engineer. As important was Dennis Hart Mahan, a professor of engineering at West Point in 1832–71. Basing his ideas on French models, Mahan taught two generations of soldiers Americanized theories of fortification and emphasized the role of field fortifications in actual operations to steady America's partially trained troops and militia. Totten's 1851 report recommended increasing the number of projected coastal fortifications from 50 (in 1821) to 186 (with 28 for the Texas Gulf Coast and the Pacific states). Estimated cost of this increased program was $25 million, with over $20 million already expended.
Coastal fortification planning inevitably touched on naval operations, and in every report the engineers remarked, usually in passing, that the navy was the first line of defense. Since actual invasion was unlikely, the engineers stressed that the proposed fortifications were to protect cities, potential anchorages, and intracoastal navigation routes, as well as to keep blockading vessels at a distance. Confronted by choice of attacking powerful defenses head‐on or landing far from their target, enemy forces might be discouraged from attacking at all. Many critics countered by asserting that fortifications alone were insufficient to protect coastal areas, suggesting various additional floating defenses or technological innovations, such as electrically detonated underwater mines demonstrated by Samuel Colt in the 1840s.
Totten's arguments for the Third System fortifications, though, overlooked the ways the Industrial Revolution was already spawning dramatic changes in artillery and ship design. Fortifications themselves were an evolved technology. In the years shortly before the Civil War, developments in metallurgy and ordnance design led to the production of heavy rifled and shell‐firing guns of enormous power. Previous heavy naval and siege guns fired shot weighing 32 to 48 pounds, the larger guns now possible fired shot weighing up to 100 pounds, with rifled artillery capable of accuracy at three or four times the previous ranges. During the Civil War, such guns, sited by engineer officers like Quincy Gillmore, smashed the thick brick and stone walls of Confederate‐occupied forts like Sumter and Pickens into rubble in hours or days. These developments were paralleled overseas, as was the development of the armored, steam‐powered, oceangoing warship.
By the end of the Civil War, it was clear that the Third System of coastal defenses was obsolete. At the same time, the rival armies learned to construct field fortifications at every opportunity. In some cases—notably the defensive works arrayed around Washington, D.C., ordered by George B. McClellan, or the trench systems created by both sides during the Siege of Petersburg, Virginia—these fieldworks become enormously complex. Built of earth reinforced by heavy timbers, they proved less susceptible to artillery damage than the seacoast fortifications. For more permanent defensive works, however, there was no consensus on a proper design other than returning to lower structures protected by earth. The Indian wars of the late nineteenth century did not provide an answer. The few western forts with walls of any kind generally had palisades of wood that could not resist artillery.
Toward the end of the nineteenth century, gun manufacturers, following William Armstrong in Great Britain, had successfully developed methods of compound manufacture to create increasingly powerful, long‐range cannon. Steel became the predominant material, and most of these new guns were breech‐loading instead of muzzle‐loading, giving them higher rates of fire. Studies suggested new, slower‐burning and more powerful propellants instead of traditional gunpowder. Warships increased in size, armor, and speed. Consequently, many army and navy officers urged improvements in U.S. armaments and urged a program of new coastal fortification. A persistent argument was that coastal defenses were a form of insurance against the destruction resulting from raids to major coastal cities.
In 1885, President Grover Cleveland appointed a board headed by Secretary of War William Endicott to study the issue. The report of January 1886 endorsed much the same kind of system demanded by the engineers, dismissed the idea of a full‐scale invasion, and linked coastal defense to the protection of the commercial metropolises of the seacoasts. It stressed in particular the use of relatively new, and still unproved, technologies such as searchlights, steel breech‐loading cannon on disappearing gun carriages, armor plate, underwater naval mines, and auxiliary vessels, many of which did not yet exist in usable form. At the time, engineers estimated the total cost of the system at around $126 million.
The enormous cost of this effort meant that it was never entirely completed. Moreover, the original proposal underestimated the increasing power and range of artillery, and thus overestimated the number of guns needed. Eventually, some 700 heavy artillery pieces, mostly 8‐, 10‐, and 12‐inch long‐range guns, were emplaced, among them several hundred 12‐inch arching‐fire mortars, along with other hundreds of smaller‐caliber, rapid‐firing guns. The largest guns were capable of firing a 1,000‐pound shell to a range of 7 or 8 miles. These were installed in fortifications that encompassed a series of connected strongpoints and batteries rather than a single, massive structure, dispersed to lessen their vulnerability to naval guns. They were low‐lying, protected by thick berms of earth to absorb heavy, high‐explosive shells, and built to take advantage of ground contours to make them less visible from the ocean. In some cases, older fortifications were rebuilt to accommodate the newer guns; elsewhere the newer works went up in the same general vicinity.
During the Spanish‐American War, despite unfounded fears of coastal raids by Spanish warships that triggered the emplacement of several hundred artillery pieces, no raiders attacked any U.S. cities or harbors. Still, the acquisition of overseas territories during the war, along with the realization of advancing military technology, persuaded President Theodore Roosevelt to create another board, this one headed by Secretary of War William H. Taft, to review the coastal fortification program. Aside from suggesting the need for defenses to guard newly acquired overseas locations such as the Panama Canal, Hawaii, and Manila Bay in the Philippines, the Taft Board limited itself to modifying minor details, reestimating costs, and changing priorities slightly. It concurred with Adm. Alfred T. Mahan (son of Dennis Mahan) that the role of a navy was offensively to seek for command of the sea, not restrict itself to direct coastal defense.
By the outbreak of World War I, moreover, battleship ordnance could once more outrange most of the guns of the shore defenses, with the plunging trajectory of naval shells making open‐topped defensive works untenable. Engineers began siting defenses farther out toward the sea from the locales they defended and pushing development of more powerful 14‐ and 16‐inch guns. Fortifications became ever simpler in design and dispersed over wider areas; 1,000 feet might separate the guns of a single battery. During the 1920s and 1930s, engineers experimented with mobile railroad‐ and tractor‐drawn guns, utilizing war time stocks of 8‐ and 14‐inch guns. Employed as armament in two dozen permanent sites were newly developed 16‐inch guns, which fired a 2,000‐pound shell to a range of 30 miles. The new threat posed by aircraft forced planners to include antiaircraft guns, and led to a design that placed the entire battery structure under up to 30 feet of concrete and earth. The first such structure was erected outside San Francisco between 1937 and 1940, and it became the prototype for the defensive works constructed during World War II. The urgent demand for defenses early in that war could only be met by almost complete standardization into two‐gun batteries, emplaced within concrete bunkers and protected by steel shields. By 1944, however, with no direct threat to American shores, construction ceased.
Field fortifications also changed during World War II, with the complex, continuous trench lines of World War I giving way to small “foxhole” emplacements for individual soldiers and weapons crews, providing greater dispersal and thus survivability from modern ordnance. In both the Korean War and the Vietnam War, in the absence of aerial and armor threat, fixed defenses in the field (around bases and other strongpoints) reappeared to some degree, with works protected by earth or sandbags. Structurally, these were similar to the semipermanent, complex entrenchments of the nineteenth century, albeit with electronic listening devices and mines taking the place of cruder systems of detection and forward protection.
During the Cold War, the greater threat to American cities came from the sky, not the sea. Reliance on coastal fortifications gave way to dependence on antiaircraft guns and missiles and early warning radar networks against bombers and then missiles. The Reagan administration accelerated research on a satellite‐based laser defense system in an attempt to protect the United States against missile attack (the Strategic Defense Initiative). Between 1948 and 1949, nearly all the larger guns of the fortifications were scrapped, marking the end of relying on such fixed defenses for the protection of the American seaboard. In the 1960s, many of the old coastal forts were turned over to the National Park Service.
[See also Battlefields, Encampments, and Forts as Public Sites; Engineering, Military.]
Bibliography
- Alex Roland, Underwater Warfare in the Age of Sail, 1978.
- Emanuel R. Lewis, Seacoast Fortifications of the United States: An Introductory History, 1970.
- Robert S. Browning III, Two If by Sea: The Development of American Coastal Defense Policy, 1983.
- Marguerita Z. Herman, Ramparts: Fortifications from the Renaissance to West Point, 1992
