Seacoast defense was a major concern for the United States from its independence through World War II. Before airplanes, many of America's enemies could only reach it from the sea, making coastal forts an economical alternative to standing armies or a large navy. Substantial fortifications were built at key locations, especially protecting major harbors. Seacoast defense also included submarine minefields, nets and booms, ships, and, later, airplanes. The U.S. Army Corps of Engineers played the central role in constructing fixed defenses, but all of the armed forces participated.
Designs evolved and became obsolete with changes in the technology available to both the attacking forces and the defenders. The evolution of the U.S. seacoast defense system is generally identified among several "systems", which are somewhat defined by the styles used, but more so by the events or trends which periodically stimulated new funding and construction. The division of the early forts into the First and Second Systems was made by later historians, and appears officially in an 1851 report by Chief Engineer Joseph Totten, probably the most prolific builder of masonry forts in American history.Wade, p. 185
After the 1940s, it was recognized that fixed fortifications were obsolete and ineffective against aircraft and missiles.
Early defenses At the beginning of the American Revolutionary War, many coastal fortifications already protected the Atlantic coast. Before independence from Britain, the colonies bore cost and responsibilities for their own protection. Urgency would wax and wane based on the political climate in Europe. Most defenses were artillery protected by earthworks, as protection from pirate raids and foreign incursions. In the American colonies and the United States, coastal forts were generally more heavily constructed than inland forts, and mounted heavier weapons comparable to those on potential attacking ships. Though seldom used, the forts were a deterrent. During the Revolution, additional forts were built by both sides, usually to meet specific threats. Those built by Patriot forces were called Patriot batteries.
First System When the United States gained independence in 1783, the seacoast defense fortifications were in poor condition. Concerned by the outbreak of war in Europe in 1793, the Congress created a combined unit of "Artillerists and Engineers" to design, build, and garrison forts in 1794, appointed a committee to study coast defense needs, and appropriated money to construct a number of fortifications that would become known as the First System.Wade, pp. 22–24
Twenty significant forts at 13 harbors were approved for construction, mostly with traditional low-walled structures with low sloped earthworks protecting wood or brick walls.Wade, pp. 55–60 The conventional wisdom was that soft earth would cushion the effect of cannon fire against the walls, and that low walls presented less exposure to projectiles. Walls were laid out at angles to each other to form a system of bastions, resembling a star layout, so that enemy forces could not mass against the bottom of a wall beneath the vertical field of fire from the wall; defenders on any wall could see and fire on the base of the adjacent walls. The angled walls also reduced the chance for more destructive straight-on hits from cannonballs. Most First System forts were relatively small, and with some exceptions mounted only one tier of cannon, on the roof of the fort. Additional "" (located near the waters the forts protected) outside the forts provided more firepower. Four of the First System forts were rebuilds of colonial forts, Fort Constitution in Portsmouth, New Hampshire, Fort Independence in Boston, Massachusetts, Fort Wolcott in Newport, Rhode Island, and Fort Mifflin in Philadelphia.Wade, pp. 10–13
Lacking trained engineers to supervise the work, Secretary of War Henry Knox hired a number of European engineers.Wade, pp. 14–15 Although some fine forts were constructed, for the most part enthusiasm and funding waned and little work was completed. Most of the partially finished earthworks and wooden structures deteriorated before they were needed to defend against the British in 1812.
Second System
In 1802, Congress separated the artillerists and engineers into separate corps and directed the Corps of Engineers to create a military academy at West Point, New York. One of the driving forces for establishing the new academy was the need to divorce the United States from its reliance on foreign engineers. In 1807–8, new concerns over a possible war with Great Britain prompted President Thomas Jefferson to renew fortification programs; this has come to be known as the Second System. One event that foreshadowed war was the Chesapeake–Leopard affair.Wade, pp. 115–44
One common weakness among the typical low-walled open bastion or star forts was exposure to enemy fire, especially to new devices designed to explode in mid air and rain shrapnel down on the gunners. Gun emplacements which were at an angle to the sea were vulnerable to a solid shot running parallel to the wall taking out a row of guns and gunners with one enfilading shot. In the late 1770s, a French engineer, the Marquis de Montalembert, advocated a major change in the design of fortresses to address these problems. His design protected a fort's gunners by placing most of them in covered casemate walls with openings for the guns. By stacking rows of casemates in high walls more guns could be mounted along shorter walls. This was particularly important for seacoast fortifications, which had only a limited time in which to fire at passing enemy ships. To build these tall forts, walls had to be built of masonry, but be very thick to withstand the pounding of cannon fire. Despite the goal of building multi-tiered forts, only a few of these were completed, notably Castle Williams in New York Harbor. Most completed Second System forts generally resembled First System forts, with a one-tier star fort supplemented by water batteries.Wade, pp. 130–31, 241–46
The Second System was distinguished from the First System by greater use of Montalembert's concepts and the replacement of foreign engineers by American ones, many of them recent graduates of the new United States Military Academy superintended by Major Jonathan Williams, who not only instructed the new engineers in new ideas of coastal defense, but also designed and constructed a prototype, Castle Williams on Governors Island in New York Harbor.Wade, p. 152
Again, several fine forts were produced, but generally projects went unfinished, and between the First System and Second System little was prepared to resist the British in the coming War of 1812. However, no First System or Second System fortress was captured by the British. The British succeeded in entering Chesapeake Bay by capturing a fort on Craney Island near Norfolk and bypassing the area's two other forts. The invasion of Baltimore was prevented by Fort McHenry and supporting forts and troops. These included shoreline batteries at Forts Babcock and Covington to the west, Fort Look-Out (or the Six-Gun Battery) on the peninsula to the rear in the west, a temporary naval battery across the Patapsco channel to the east at Lazaretto Point, and sunken ships blocking the channels on either side of Fort McHenry, along with 20,000 militia dug in on the east side of the town at "Loudenschlager's Hill" (later "Hampstead Hill" in today's Patterson Park).Wade, pp. 178–179 The intense all-night bombardment of Fort McHenry by the British ships offshore was memorialized by Francis Scott Key, a Baltimore lawyer who witnessed the ferocious attack from one of the vessels, and put down his thoughts watching the barrage—which failed to either destroy the fort or subdue its defenders—in a four-stanza poem, which became known as "The Star-Spangled Banner" and later became America's national anthem. In some cases even incomplete forts (some with fake wooden cannon barrels painted black pointed out the embrasures) were sufficient to deter attack from the sea. But, undefended and unfortified, Washington, D.C., the national capital, was burned after the land militia forces were routed at the Battle of Bladensburg northeast of the capital in Prince George's County, Maryland. Washington had one fort, which the British bypassed, Fort Washington on the Potomac River just below Alexandria, Virginia, whose commander ordered the magazine blown when the passing British fleet appeared nearby, after the British had already occupied Washington.Wade, pp. 177–178 The present Fort Washington was built on the site of the destroyed Fort Washington in the early 1820s as part of the Third System.Weaver, pp. 123–124 Among the many important and historic documents lost in the British burning of the Library of Congress were the plans to the first Fort Washington (begun as Fort Warburton) and other Second System forts.
Third System
In 1816, following the War of 1812, Congress appropriated over $800,000 for an ambitious seacoast defensive system which was known as the Third System. A Board of Engineers for Fortifications, appointed by President James Madison, visited potential sites and prepared plans for the new forts. The Board's original 1821 report established the policy which would remain in place for most of the 19th century. The original report suggested 50 sites, but by 1850 the board had identified nearly 200 sites for fortification. The Army built forts at 42 of these sites, with several additional sites containing towers or batteries.
The forts were originally intended to mount mostly 42-pounder (7-inch or 178 mm) seacoast guns; however, due to a shortage of these weapons many 32-pounder (6.4-inch or 163 mm) seacoast guns and 8-inch (203 mm) and 10-inch (254 mm) columbiads were mounted instead.
The main defensive works were often large structures, based on combining the Montalembert concept, with many guns concentrated in tall, thick masonry walls, and the Vauban concept, with layers of low, protected-masonry walls. Most Third System forts had at least two tiers of cannon; the First and Second System forts often had only one tier. Construction was generally overseen by officers of the Army's Corps of Engineers. Smaller works guarded less significant harbors. U.S. Army engineer officer Joseph Totten and former French engineer officer Simon Bernard (commissioned a brevet brigadier general in the U.S. Army) designed the larger forts and key features of most of the smaller forts, such as the Totten casemate, which allowed a good field of fire with a minimal embrasure size.Weaver, pp. 3–5, 11–12
By the end of the Third System in 1867, 42 forts covered the major harbors along the coastline. While most of the forts were completed, several of the forts—mostly in New England—were still under construction. A few of these forts, such as Fort Preble, Fort Totten, and Fort Constitution, were readied for armament even though they were far from complete.
The Corps of Engineers listed the forts from northeast to southwest, then to the Pacific Coast. The same order is used here for the new-construction forts of the Third System: Penobscot River, Maine: Fort Knox; Kennebec River, Maine: Fort Popham; Portland Harbor, Maine: Fort Gorges, Fort Scammell, Fort Preble; Kittery Point, Maine: Fort McClary;Fort McClary, Kittery Point, Maine Portsmouth, New Hampshire: Fort Constitution; Boston Harbor, Massachusetts: Fort Warren, Fort Independence; New Bedford, Massachusetts: Fort at Clark's Point (later Fort Rodman);Also called Fort Taber Newport, Rhode Island: Fort Adams; New London, Connecticut: Fort Trumbull; New York City: Fort Schuyler, Fort at Willets Point (later Fort Totten), Fort Tompkins, Fort Richmond, Fort Hamilton, Fort on Sandy Hook, New Jersey (later Fort Hancock); Pea Patch Island, Delaware: Fort Delaware; Baltimore Harbor, Maryland: Fort Carroll;