Because an invading enemy normally required a port to sustain operations, defense of the most important harbors would largely secure the coastline. Coast defense includes all measures taken by naval forces, artillery, etc., to provide protection against any form of attack at or near the shoreline. Harbor defense includes the defense of a harbor or anchorage and its water approaches against external threats such as: submarine, submarine-borne, or small surface craft attack; enemy minelaying operations; and sabotage. The defense of a harbor from guided or dropped missiles while such missiles are airborne is considered to be a part of air defense.
Throughout most of its history, the United States, separated from the other powerful nations of the world by large bodies of water, relied on coast defense to deter enemy invasion. This defensive measure depended on fortifications but also included submarine mines, nets, and booms; ships; and airplanes. Thus, all of the country's armed forces participated in coast defense, but the US Army Corps of Engineers played a central role.
Initially, the Continental Army had no military engineers. In June 1775, it received authorization to appoint some engineers, and in March 1779, the Continental Congress approved their formation into a "Corps of Engineers." Besides overseeing coastal fortification construction, these engineers placed obstructions in channels and harbors and stretched chains across rivers to prevent the passage of enemy ships. They also experimented with submarine mines, which they called torpedoes.
When the American Revolution began in 1775, many coastal fortifications already dotted the Atlantic coast. Local communities, colonies, and military engineers constructed these defenses, usually earthworks, as protection from pirate raids and foreign incursions. Although seldom used, the forts were a deterrent. Much additional fortification construction occurred during the American Revolution. Many of the defenses were simple earthworks, usually erected to meet specific threats.
The forts of the young United States evolved slowly in response to threats of war and continuing advances in weapons technology. A national program of fortification building known as the First American System began in the 1790s. In 1794, under the threat of war with England, Congress passed its tirst fortification construction bill, which authorized work at 20 locations on the Atlantic coast. A few months later, it added one more harbor - Annapolis, Maryland - to the list of sites. The Secretary of War instructed that these defenses consist of earthen or timber batteries, blockhouses, barracks, and magazines. Mostly of earthen construction, the First System forts quickly fell into decay after the war scare passed.
With the threat of war increasing after a battle between British and American ships, known as the Chesapeake incident, Congress in 1807 authorized another construction project for coastal fortifications, known as the "Second System." Congress, fearing a second war with England, passed a large appropriation bill for fortifications. Thanks to the Military Academy, which then provided a rudimentary military engineering education, the United States had American military engineers available to plan and supervise fortification construction. Differing considerably from earlier coastal defenses, these new works consisted of open batteries, masonry-faced earth forts, and more permanent all-masonry ones. Many of these forts were rushed into service during the War of 1812. During the second war with England, in 1812-15, the mere existence of these forts generally deterred the British from attacking the defended harbors. In a few cases, the British did assault the defenses. At Baltimore, in 1814, Fort McHenry and its subsidiary fortifications halted a determined landing attempt. In general, American seaports had one or two fortifications of at least moderately respectable size and strength. Not one of the forts built by the Corps of Engineers fell to battle during the War of 1812.
The concept of seacoast defense became extremely important in the United States after its severe lack of preparedness during the War of 1812. The embarrassing destruction of Washington, with the concurrent successful defense of Baltimore by Ft. McHenry, pointed to the potential value of well-designed fortifications.
The Third System of coastal fortifications was designed to protect important harbors and cities, interior navigation, and navy yards. Without the urgency of a specific threat, coastal defense under the Third System grew slowly and carefully. The Third System of forts, meant to provide a comprehensive program of coastal defense with advanced armaments. It was intended that the new fortitications, large and small, would provide adequate, permanent security for the entire country.
The best and brightest graduates of the US Military Academy became engineers, and many were assigned to work on these fortifications. Robert E. Lee worked all along the East Coast building brick forts to defend the United States from foreign enemies. Fort Pulaski on the Savannah River in Georgia, Fort Totten in New York and Fort Jackson on the Mississippi were just some of the forts strengthened or built during this time. After more than 40 years of construction, the Third System was nearing completion by 1860.
One of the most important developments of the Third System was the use of all-masonry fortifications, rather than the combination of earth and masonry that characterized earlier structures. The use of masonry allowed the engineers to construct casemates, or gun portals within the walls. Although primarily intended to protect the gunners during an attack, casemates also allowed engineers to multiply the number of guns at a single fort by placing tiers of guns inside the walls. Thus, this new series of forts could produce a formidable array of firepower. Casemates were not so welcome, however, to the soldiers assigned to coastal forts. With few exceptions, the Corps of Engineers did not build barracks at these forts.
Edmund Pendleton Gaines, commander of the Western Division of the US Army (1836-1844), advocated a strong network of military railroads, turnpikes, and canals connecting the frontier to the interior. He also advocated floating batteries as a means of coastal defense. Cannons remained unchanged from the 15th to the mid-19th century. For more than 300 years, fortifications were designed in this unchanging environment. By the time of the American fortification program in the early-19th century, forts were only vulnerable to protracted army sieges. They were the perfect defense against naval enemies.
The Civil War saw the use of the underwater mine as a supplementary coast defense measure. The Confederacy, without a large navy to protect its harbors and rivers, used submarine mines-often called torpedoes-to protect its waters from attacks by Union ships. Matthew Fontaine Maury, first chief of the Confederate Torpedo Bureau, used mostly contact mines, which exploded upon impact with a vessel, but experimented with other types. This defensive measure inspired David G. Farragut's oflen-quoted statement, "Damn the torpedoes, full steam ahead," uttered during his attack at Mobile Bay.
By 1865, rifled cannon and ironclad warships had rendered masonry forts obsolete. During the Civil War, the Union Navy discovered that its steamships and ironclad vessels could run past Third System forts with acceptable losses. After the war, naval technology advanced rapidly, especially in the European navies, while America's coastal defense system remained stagnant. Increased steel plating and improved steam propulsion made ships less vulnerable to the old smooth-bore guns of America's forts. More importantly, improvements in naval ordnance resulted in breach-loading, rifled guns that could demolish a fort's masonry walls.
In the 1880s and 1890s the US replaced masonry forts with simpler reinforced concrete structures. While the structures were simplified, the weapons mounted on them were vastly more complex than the cannon of the pre-Civil War era. During the 1880s a special board convened by Secretary of War William Endicott made sweeping recommendations for new or upgraded coastal defense installations and weapons systems. The primary artillery pieces were the 12-inch mortar and the "disappearing" gun (available in at least five sizes), supplemented by smaller armament. Foreign navies eventually developed new guns that exceeded the range of these weapons, so the Coast Artillery responded with 16-inch howitzers and guns.
The weapons for these concrete forts, called Endicott batteries, represented a great technological leap. Weighing as much as 58 tons, these guns could fire projectiles that were twice as heavy and could go three times farther than the largest cannon in the pre-Civil War arsenal. Large carriages raised the guns over walls for firing and lowered them for reloading.
Before the advent of air power and submarines, the main defenses America relied upon to protect against enemy attack were the coastal artillery batteries. The guns were aimed on the basis of data received from observers stationed some distance away, so the Army needed a reliable method to transmit the data. However, the noise in the gun pits was quite deafening when the batteries were firing. Using a telephone or telegraph under these conditions was not practical. So, in the 1890s telautographs were installed in most important American coastal forts on both coasts. The telautograph reproduced handwriting and drawings by transmitting the movements of an electromagnetically-controlled pen along a line to a similar pen at the receiving end. The military version of the telautograph was designed for ruggedness and reliability. The receivers were enclosed in heavy brass, waterproof cases suspended on shockproof mounts. Messages appeared behind a plate glass window, allowing the operator to read the messages without opening the case. An electric bulb inside the case allowed night reading.
As the 20th century approached, military strategists realized that heavy (fixed) artillery required a very different training program than lighter, mobile field artillery. The obvious solution was to divide the Artillery Corps into two new branches: Field Artillery and Coast Artillery. This process began in February 1901 with the creation of dozens of Coast Artillery companies. Six years later the venerable Artillery School at Fort Monroe became the Coast Artillery School. It operated at this post until 1946, serving as the principal training center for most officers and many enlisted men in this branch of the Army.
After the American Civil War congressmen were devoted to the idea of coastal defense so that they could tell their constituents that Charleston or Portsmouth or Boston would be protected by a single ships. This was a great comfort to people who lived there.
In light of Civil War experience, the Engineers were in a quandary over the kind of defenses needed. They were sure, however, of the need for a practical submarine mine. The Corps Engineer School of Application began experimenting with buoyant torpedo (submarine mine) and connections. Disregarding contact mines, they attempted to develop a reliable electrically detonated device. As an outgrowth of this work, the War Department established the School of Submarine Defense and Torpedo School at Fort Totten in 1901 when it transferred responsibility for submarine mines to the Coast Artillery Corps.
The invention of the "automobile torpedo" prompted the Navy to experiment with a new type of vessel, the torpedo boat, using the Torpedo Station and Naragansett Bay. The first of these boats, built in 1886 and 1887, were only 139 feet long and displaced only 105 tons, with a crew of two officers and 20 men and an armament of three above-water torpedo tubes. They were intended primarily for a coastal defense role, with an expected capability to maneuver quickly against a larger ship and fire their torpedoes. In practice, the torpedo boats did not fulfill their expectations.
By the end of the 19th century, the United States Navy, without so much as a single modern battleship to its name, ranked eleventh among the world's fighting fleets, behind Turkey and Austria. The Army was even worse off. In 1890 it fielded a total force of 28,000 officers and men, fewer than Bulgaria at the time. Coastal defense consisted of scattered batteries of mostly Civil War-vintage artillery. Other advanced nations must have had a good laugh when they compared notes about America's creaking military machine. But they would have missed the point. Though weak, this army and navy were equal to America's security needs in the 1890s. America had no foreign enemies, and the oceans would have kept them safely at bay. Americans were not alarmed to see their coastal guns gathering rust because there was little likelihood that those guns would be needed. In other words, there was appropriate proportionality between any risks to national security and the means available to protect against those risks.
But the late 19th Century naval strategist Alfred Thayer Mahan believed that a secure nation required more than coastal defense. It required building new and bigger ships and deploying them all over the world to impress friends and intimidate enemies. This new vision called for fast, heavily-gunned, long-endurance steamers to replace the Navy's preoccupation with harbor and coastal defense, and with blockade, by a concept of command of the seas. The advent of new technology soon led to new concepts of naval strategy, as Navy leaders turned towards fighting major fleet actions.
President Theodore Roosevelt's shipbuilding program, started in the early 1900's, provoked intense opposition among large well-organized groups of educators, clergymen, and other citizens. Isolationist and pacifist groups opposed overseas expansion, demanded a reduction in American naval armaments and an end to what they perceived to be United States militarism. In 1908, the name of U.S. Steel baron Andrew Carnegie headed a list of nearly 400 citizens of New York City who submitted a petition to the committee denouncing Roosevelt's proposed $60,000,000 naval construction program. Form petitions signed by hundreds of theological students, Pennsylvania Quakers, political liberals, constitutional advocates, and dedicated peace groups continued to decry naval expansion in succeeding years.
The submarine seaport defenses in 1904 were under the jurisdiction and control of the Army. Army strategies for submarines were to replace and supplement fixed mines, pick up and repair defective cable joints and junction boxes, and prevent countermining by enemy submarines. The Navy Department board was adverse to the purchase of any more "submarine torpedo boats" and wanted to experiment with them to ascertain their full value. The Army board wanted to use submarines for mining and coastal defense and recommended that submarines be put under Army supervision as a distinct coast defense.
Initially the US Navy separated submersibles into two groups according to mission. "Boats" of the N and O classes, as well as some of the E type, patrolled US coasts and harbors in the service of a defensive strategy. Other submarines drew assignments that sent them to hostile European waters after 1917. Subsequent Navy Department planning for submarine operations reflected prevailing surface warfare thinking, which perceived the submersible as a type of destroyer or torpedo boat that should operate with the battle fleet.
Harbor defenses consisted of permanently installed guns of various calibers, which could be supplemented in an emergency by mobile coast artillery guns and controlled mine fields. Their purpose was, first of all, to guard the defended area against invasion and capture; secondly, to protect the area against naval bombardment, and shipping against submarine or surface torpedo attack; and finally, to cover the seaward approaches to the principal naval anchorages sufficiently far out to enable ships of the United States Navy to emerge and meet attack. Indeed, the location of naval shore installations and fleet anchorages was the most important factor in determining the location of Army harbor defenses, and the Navy's insistence on the necessity of such defenses was the principal reason for their retention and improvement. Adequate protection of bases and ships in port freed the Navy for offensive action. The War Department was also well aware of the fact that the maintenance of permanent seacoast defenses gave major coastal cities a sense of security which might help to ensure against an unsound dispersion of the Army's own mobile ground and air forces in a war emergency.
When World War I began, some Americans felt insecure about United States coast defense. Many weapons were outdated, guns on European naval vessels outranged those of the US Coast Artillery Corps, and submarines could enter harbors undetected. To remedy this situation, the Navy and Army installed submarine nets in various harbors, the Coast Artillery Corps laid submarine mines, the Corps of Engineers erected new batteries, and Congress provided for an increase in the armed forces. As more and more men embarked for Europe and the enemy threat to American shores abated, personnel and funds for coast defense declined.
In studying the situation in 1923, the War Department decided that either a larger fleet or a much larger number of aircraft would provide more effective protection for harbor areas than the existing defenses, but it also held that the use of either would be highly uneconomical. It concluded, "when it comes to preventing enemy ships from sailing into a harbor and taking possession, the cheapest and most reliable defense appears to be guns and submarine mines." Primarily for the latter reason, the General Staff decided in 1923 that permanent seacoast fortifications should still be considered essential. It recommended the abandonment of a number of harbor defenses that were no longer of military value and concentration on the improvement of those remaining, particularly by providing them with new long-range guns and more antiaircraft protection. It also urged more combat aviation to supplement harbor defenses. It called for the retention of permanent defenses for eighteen coastal areas-the same eighteen that were to be included in the modernization program of 1940 and that still possessed fixed defenses in 1945.
In 1920, Congress passed the Army Reorganization Act, which made the Air Service a combatant arm of the Army. General Billy Mitchell, who had become Assistant Chief of the Air Service, went on the offensive. He reasoned that the Air Service would stand little chance of gaining independence unless it had a unique mission. Mitchell, an outspoken advocate of strategic bombing, argued that the airplane made the battleship obsolete; therefore, the Air Service could most effectively accomplish the mission of coastal defense. To prove his point, Mitchell arranged an invitation to participate in an aerial bombing demonstration with Martin MB-2 bombers and three captured German ships. All three ships, including the "unsinkable" Ostfriesland were sunk by Mitchell's bombers and Navy and Marine Corps aircraft. Mitchell continued to harass his superior officers over the need to enlarge the Air Service and improve its equipment. In 1925, he deliberately provoked a court-martial, was convicted, and left the Army in early 1926.
The Army Air Service was renamed the Army Air Corps in 1926, to denote its offensive, striking capabilities and was designated the General Headquarters Air Force in 1935, when coastal defense and an independent mission was established. The development of large aircraft by the Air Corps had been justified as a means of coast defense. In June 1934 the War Department had approved Project A for exploring the problem of maximum range for a reconnaissance-bomber; this project brought forth the B-15. In May 1935 the Secretary of War approved a bigger and better venture, Project D, aimed at still greater size and range, which produced the giant B-19.73 Both of these costly experiments were supported by the War Department, not to secure prototypes for strategic bombardment, but to develop the most efficient aircraft for use in coast defense. During the period that these projects were under way, Air Corps leaders continued to stress that they desired large planes only for protection of the hemisphere.
Maj. Gen. Oscar Westover, Chief of the Air Corps, related his plea for a stronger air force to the military dangers abroad. Addressing the National Aeronautical Association in November 1936, Westover declared: "If and when the great European conflict occurs, the only way in which the neutral nations in the world can keep out of that conflict is to have such a strong national defense that none of the belligerents involved dare violate their neutrality." No suggestion was given of possible offensive operations by the big bombers. Likewise, Maj. Gen. Frank M. Andrews, commanding the GHQ Air Force, related his arguments for long-range aircraft to the coast defense requirement. The advantages of the large plane over the smaller one, said Andrews, were greater power of self-protection, less danger of forced landings, economy of operation per bomb delivered, and ability to contact the enemy sooner and to hold him longer under surveillance and attack. In response to a query from Maj. Gen. Stanley D. Embick of the General Staff, Andrews stated flatly that the air weapons under development were purely defensive. "It is utterly absurd to consider them as anything else and I think we should emphasize this point on all occasions."
A year later found Andrews stressing the same theme in a lecture before the Army War College. Seeking to counteract criticisms of the big bomber projects, he told his audience: "From some sources comes the statement that the modern development of large bombers is for the purpose of aggressive action on the part of the United States. Often we hear of our large bombers spoken of as 'Weapons of Offense,' 'Superbombers,' and similar appellations. These terms are unfortunate and misleading."
As World War II approached, Congress provided larger appropriations for fortification construction. Fixed positions once again became the primary defense, relegating mobile artillery to a secondary role. Except for a few variations in design and gun sizes and experimentation with turrets, the Corps of Engineers began erecting a standard two-gun concrete battery. Between the guns, the battery encased the magazine and power plant and sometimes the plotting room and quarters under a reinforced concrete shield covered by many feet of earth. The big guns, 16- and 12-inch, were in casemates with only part of their tubes protruding. Mounted outside the battery, the smaller 6-inch guns had an armored shield. At various distances from the batteries were base-end stations-bservation towers-where personnel could watch enemy movements, assess the effect of artillery fire, and furnish coordinates to the plotting room.
Until the nation went to war in December 1941 the military preparations for guarding the continental United States centered around four lines of activity: harbor defense, defense against air attack, civilian defense, and the protection of vital nonmilitary installations. Although primarily concerned with measures for protection against bombardment from the air, the Army did not entirely neglect the fixed coastal defenses that offered limited protection against surface attack. Seacoast defense against a determined surface attack or invasion would have required the integrated employment of all types of Army mobile ground and air forces in addition to the harbor defense units, but plans for employing mobile forces for this purpose remained comparatively nebulous until after the United States entered the war.
The end of naval armament limitations during the 1930's had also reemphasized the need for better long-range guns; to meet this need the Army had adopted the 16-inch barbette carriage gun as the standard harbor defense weapon against capital ships, but only a few had been installed by 1940. The 16-inch guns had a maximum range of about twenty-five miles, and, at least theoretically, could keep any hostile ship at a safe distance from any of the twelve harbor areas where they were to be installed under plans adopted in 1940. After Pearl Harbor, railway guns were used at a few east and west coast locations but were replaced as soon as other weapons became available. By July 1941 only four 16-inch gun batteries were ready for action, and construction work had been started on only five others. By then it appeared that the 16-inch gun program could not possibly be completed for several years and that in the meantime the planned expansion of American air and sea power would make the full program unnecessary.
As an integral part of harbor defenses the Army for many years had planned to install strings of electrically controlled mines across the ship channels and narrows of port approaches. Army mine fields were intended primarily to prevent submarines from slipping into inner harbor areas. Controlled mine fields, as provided for in harbor defense projects, were quickly installed in many harbor entrances after the declaration of war. They caused much trouble, since the mines then available were of a buoyant type that rested only fifteen feet below the water's surface, and passing ships frequently fouled the connecting cables. In 1943 the Army replaced the buoyant mine with a newly developed ground mine that all friendly ships could clear without danger and that had an explosive charge powerful enough to destroy any sort of enemy vessel that might attempt to intrude. Ground mine fields remained in position until the summer of 1945.
The era of seacoast defense closed at the end of World War II. The development of aircraft and nuclear weapons rendered large coastal artillery obsolete. Most artillery bases were closed in the late 1940s, with the weapons and structures sold for scrap.
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