Evolution of Guns in America's Seacoast Defensive Forts

Seacoast defensive forts were established early in American history to protect harbors and coastal towns. Coastal forts continued to be built through World War II. Early forts were usually built of earth, wood, and stone, or any materials they had on hand. Later on, forts would be built of brick and masonry followed by forts of reinforced concrete and steel. And as the forts grew stronger and larger, the guns inside the forts also underwent technological advancement.

Before and during the Revolutionary War, Americans built seacoast forts to protect their cities near the water. Usually built of earth and wood, these forts were most commonly armed with 18- and 24-pounder European cannon (pounder refers to the weight of the solid cannon ball the gun fired). These cannon were made of cast-iron and were muzzle-loading guns. Muzzle loading means that the guns had to be loaded from the front or muzzle. Black powder (before the invention of modern gunpowder) would be "rammed" in by the crew. Then the cannon ball would be "rammed" home. These guns could fire a cannon ball 3/4 of a mile to one-mile using a six-pound charge of black powder. In fact, the first victory for the American's over regular British troops occurred when Patriots at Fort Sullivan defeated the British Navy outside of Charleston, South Carolina, on June 28, 1776.

Cannon used by seacoast forts were to be mounted as close to water level as possible. Then gunners could skip the cannon ball across the water. If the cannon ball hit the ship at water level, then the hole would let water in and the ship would sink. Plus, in the heat of battle, gun crews would not have to worry about aiming. Instead they could point the gun in the direction of the enemy ship and fire.

During the Revolution, many of America's coastal forts fell into disrepair. After the war was over Congress authorized the construction of new coastal forts. New forts were built between 1794 and 1807, and were called the "First" and "Second" Systems of fortifications. Guns in these forts differed little from the guns used during the Revolution. All the guns were still muzzle loading, smoothbore cannon of the 18- and 24-pounder variety. Although you would now see heavier 32- and 42-pounder's entering service.

However, the weakness of America's seacoast defenses was exposed when the British invaded Washington DC during the War of 1812. Following this war, Congress approved even another system called the "Third System" of coastal fortifications. New heavier cannon were needed to arm these larger brick and masonry forts. Between 1840-1860, three men: George Bomford, Thomas Rodman and John Dahlgren; would develop the next generation of heavy guns. Bomford designed a new type of gun called the "Columbiad." A versatile weapon, the Columbiad was produced in 8-and 10- inch calibers and could fire at level or high elevations. They could fire, respectively; 64- or 125-pound cannonballs almost 3 miles.

Lt. Thomas Rodman's contribution was in gun manufacturing. All cannons up to this time were cast solid and bored out after cooling. Basically guns cooled from the outside in. Rodman decided to cast the gun hollow and run water into the barrel as it cooled. This allowed the gun to cool from the inside out and gave it greater strength. Rodmans of up to 15 and 20 inch caliber were now possible. A 15-inch Rodman could fire a 440-pound cannonball more than 4 miles.

John Dahlgren also produced larger guns for the U.S. Navy. His guns have a distinctive "soda bottle" shape caused by extra thick walls around the breech of the gun. The U.S. Navy's Monitor was armed with two 11-inch Dahlgrens in its famous battle with the Merrimack (C.S.S. Virginia).

Even though these guns were bigger and could fire farther, they still were smoothbore, muzzle-loading, cast-iron, guns. A new technology developed long before the Revolutionary war was slowly making its way into seacoast gun manufacturing.

Rifling was spiral groves inside a gun barrel that caused the shell to spin out of the gun. Much like a football thrown with a spiral, the shells could fly farther, faster, and with much greater accuracy. Used in small arms prior to the Revolution (i.e. Pennsylvania long-rifles) it had not worked well in cannons. But, just prior to the American Civil War, much had been done to develop rifled cannon in England.

Whitworth, Armstrong and Blakely rifled-cannon were all of British manufacture incorporating the new rifling technology. The Confederates had even received a 3.5-inch Blakely gun in Charleston before the war, and it was used in the bombardment of Fort Sumter. Its use ushered in a new era of weaponry and the end of brick-made forts.

During the Civil War a man named Robert Parrott introduced a new rifled gun design that changed seacoast guns forever. The Parrott Rifle was a simply designed, rifled, cast iron gun, with an extra band of iron around the breech. Known for its ease of operation and effectiveness, Parrott's were made in 10-, 20-, and 30-pounder field models and 100-, 200- and even 300-pounder seacoast guns. The Parrott would become the most common rifled gun of the war. It was Parrott's rifles that forced the surrender of Fort Pulaski and reduced Fort Sumter to rubble during the war. In fact, during the siege of Charleston, Union forces fired a 200-pounder Parrott more than four miles into downtown Charleston introducing a new type of warfare on civilians.

Confederates also built their own rifled guns to protect their harbors from Union ironclads. Lacking the industrial might of the North, Southern factories took old smoothbore weapons and rifled the barrels and placed an extra layer of wrought iron over the breech to give it greater strength and accuracy. In this way, a rifled and banded 42-pounder increased it's range from one mile to two miles. They also developed their own version of the Parrott Rifle called the Brooke Rifle. However, although as powerful and accurate as their northern counterparts, industrial deficiencies did not allow many of these guns to be made.

Following the war, plans were made to rebuild or modernize the "Third System" forts. However, by 1875, Congress lost interest and funding dried-up for modernization of the old forts. But, in 1885, Secretary of War, William C. Endicott, called for the building of new reinforced concrete batteries, armed with the most modern weapons to be constructed. Although not built right away, Endicott era batteries would be constructed with the outbreak of the Spanish-American War in 1898-1899.

Endicott batteries were built of reinforced concrete, sometimes 20-inches thick, and buried behind tons of dirt. Armed with large, rapid-fire, breech-loading guns (breech-loading means the guns were now loaded from the rear instead of the muzzle) of 8-, 10-, and 12-inch caliber that could fire a 1,000 pound shell almost 10 miles. These weapons were designed to match any battleship in firepower.

One of the most common type seacoast gun at this time was called a "Disappearing Gun," mainly referring to its carriage. Upon the firing of the gun, its natural recoil brought the gun down behind the battery's wall. The crew could then load the gun in relative safety. When the gun was ready to fire, a lead counter-weight was tripped and the gun rose above the wall into firing position.

Other types of weapons introduced in seacoast defense at this time were "heavy mortars" and smaller rapid-fire batteries. Heavy mortars of 12-inch caliber which were mounted in groups of two or four designed to drop a grouping of 700-pound shells onto incoming enemy ships. Another type of weapon was the rapid-fire battery. Batteries would consist of steel, breech-loading weapons of smaller calibers such as the 4.75-inch Armstrong gun and the 3-inch, or 15-pounder gun. Minefields had been laid at entrances to harbors to protect them from enemy ships. These smaller weapons were installed to protect minefields from fast minesweeping boats. Unfortunately, most of the huge seacoast guns, heavy mortars and rapid-fire guns were scrapped during World War II because the military needed the metal. In addition, these guns were of little use against German U-boats (submarines) which were now the biggest threat to America's harbors.

In the 1920's the last guns developed for coastal defense were introduced. These were massive 16-inch weapons that could fire a shell weighing more than a ton over 30 miles. The gun itself weighed over 200 tons. But, because of the introduction of aircraft in WWI, much attention was also paid to anti-aircraft units in coastal defenses. Protection for the big guns was a must, so 6-inch guns and batteries of 90-mm guns had been added as anti-aircraft and anti-torpedo boat defenses. Yet few of the new coastal defensive batteries were completed during the war. With the development of long-range bomber aircraft, missiles, rockets, and amphibious assaults, coastal artillery was outdated. By 1948, new construction was ended and by 1950, the Coastal Artillery was abolished as a separate arm of the U.S. Army.

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Last Updated:Tuesday, 09-Jan-01 14:45:23