Seacoast defense in the United States

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.

[2] 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.

[8] 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.

[9] 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.

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.

[17] Again, changes in technology affected design; the higher velocity ordnance of new rifled cannons crushed and penetrated the masonry walls of Third System forts.

During the Civil War, naval officers learned that their steamships and ironclad vessels could run past Confederate-held Third System forts with acceptable losses, such as at Mobile Bay.

From the 1870s to the 1890s, larger and more powerful breastwork monitors were produced, such as the Amphitrite class, while the ocean-going navy was slow to make the transition to steel hulls and armor plating.

As early as 1882, the need for heavy fixed artillery for then modern seacoast defense was noted in 21st President Chester A. Arthur's Second Annual Message to the Congress (later known as the State of the Union address, after 1913), as follows: I call your attention to the recommendation of the Secretary and the board that authority be given to construct two more cruisers of smaller dimensions and one fleet dispatch vessel, and that appropriations be made for high-power rifled cannon for the torpedo service and for other harbor defenses.

Since that time, the design and construction of heavy ordnance in Europe had advanced rapidly, including the development of superior breech-loading and longer-ranged cannon, making U.S. harbor defenses obsolete.

In 1883, the United States Navy began a new construction program and class of steel-hulled, steam-powered propeller warships with rotating gun turrets with an emphasis on offensive rather than defensive vessels.

Following the infamous and tragic explosion and sinking of the new battleship USS Maine on 15 February, an Act of Congress a month later of 9 March 1898 authorized the construction of batteries that could be rapidly armed at numerous East Coast locations.

[25][30] Circa 1901 the Coast Artillery took responsibility for the installation and operation of the controlled mine fields from the Corps of Engineers; these were planted to be under observation, remotely detonated electrically, and protected by fixed guns.

Most of the changes recommended by this board were technical; such as adding more searchlights, electrification (lighting, communications, and projectile handling), and more sophisticated optical aiming techniques.

In an exercise in 1907 at Subic Bay, Philippines, a U.S. Marine battalion of the Advanced Base Force commanded by Major Eli K. Cole emplaced forty-four heavy guns for coast defense in a ten-week period, due to the Eight-eight fleet war scare with Japan.

[35][36][37] These guns were operated by the Marines until circa 1910, when the Coast Artillery Corps' modern defenses centered on Fort Wint on Grande Island were completed.

After the outbreak of war in the Pacific on 7 December 1941, Fort Drum withstood heavy Japanese air and land bombardment as it supported U.S. and Filipino defenders on Bataan and Corregidor until the very end on 6 May 1942.

Curiously, despite the rise of air power in World War I, it received little consideration in U.S. coast defense design until the late 1930s, probably due to the emergence of Japanese aircraft carriers as a threat.

In response to the rapid improvements in dreadnought battleships, approximately 14 two-gun batteries of 12-inch guns on a new M1917 long-range barbette carriage began construction in 1917, but none were completed until 1920.

[43][44] During World War I, the U.S. Navy implemented a more successful program that delivered five 14"/50 caliber railway guns to France in time to support the final Allied offensives.

The General Staff reconfirmed a commitment to artillery and mines as the most practical and cost-effective methods for seacoast defense, as an alternative to a larger Navy or Air Corps.

Based on the Coast Artillery's experience operating heavy weapons in World War I, especially the French-made 400 mm (15.75 inch) Modèle 1916 railway howitzer, new barbette carriages were designed with an elevation of 65 degrees to allow plunging fire as enemy ships approached.

The first batteries of heavy guns constructed after World War I were, somewhat inexplicably, completely open except for camouflage, but mounted long-range weapons set back from the coast out of direct observation from the sea.

[60] However, from the late 1930s (in most cases beginning in 1942) these batteries were mounted under thick concrete casemates covered with vegetation to make them virtually invisible from above and well protected against bombing.

Circular concrete platforms called "Panama mounts" were constructed in existing and new defenses to improve the utility of these weapons, particularly early in World War II.

Eight 8-inch railway guns had been deployed to the Philippines in 1940, but six were destroyed by air attack while entrained in response to the initial landings, and the other two were placed in fixed mountings on Corregidor and Bataan, but lacked crews and ammunition.

As the areas of combat became more distant from the U.S. and as naval threats were essentially removed, defending harbors against ships became a low priority, and as the new coast defense batteries were completed, almost all of the older seacoast guns were scrapped to become new weapons.

[73][74] Two related aspects of seacoast defense in the early part of the war were coastal beach patrols in the continental United States (CONUS) and the maintenance of mobile forces there to respond to potential enemy raids.

[75] On the night of 12 June 1942, a patrolling Coast Guard sailor observed German agents landing from a U-boat near Amagansett, Long Island, New York.

[82] With the advent of numerous intercontinental ballistic missiles, the Nike and BOMARC systems were considered obsolete by the mid-1960s and the installations were removed in the early 1970s, ending nearly 200 years of American coastal defense.