Category: Ammo

The nuclear arms race began during World War II, with the United States and the U.S.S.R. competing for supremacy for decades after the war’s end. Eventually, several other countries joined in, creating nukes for their own protection from their enemies. However, no country could match the scale of nuclear development of the U.S. and the U.S.S.R. superpowers.

After the U.S. destruction of Nagasaki and Hiroshima through the development of nuclear weapons as part of the Manhattan Project, the Soviet Union’s nuclear program went into high gear. While it was thought the Soviets would not be able to create a bomb for several years, they were able to complete their version of the Fat Man bomb, the RDS-1 (also known as the Joe-1 by the Allies in reference to Joseph Stalin) in 1949 due to espionage within the Manhattan Project.

In the 1950s, civilian views on nuclear weapons were a combination of fear and patriotism. Many Americans lived in fear of nuclear war with the Soviets, and the concerns of the long-term effects of radiation exposure was also high, prompting people to construct fallout shelters and stockpile food and supplies.

The Navy Needs a Nuke?

As a result of this arms race, the U.S. military had a prodigious amount of nuclear weapons. The U.S. Army had the Davy Crockett recoilless smoothbore gun, the Special Atomic Demolition Munition, aka the backpack nuke, the Honest John medium-range missile, and atomic cannons with nuclear artillery shells.

The U.S. Air Force had the Mark 4 and B43 gravity bombs, the Atlas ICBM, and, starting in the early 60s, the Titan II ICBM equipped with a single nine megaton warhead.

The U.S. Navy had the Polaris submarine-launched ICBM and the Regulus cruise missile for surface vessels and submarines. Additionally, the Navy employed a number of aircraft, including the Douglas A-3 Skywarrior strategic bomber, capable of delivering a nuclear strike. The only weapon system without a nuke was the U.S. Navy’s big guns on the powerful Iowa-class battleships, but that would soon change.

The Mark 7

The main armament of the Iowa-class battleships, the remarkable Mark 7 gun weighed 267,900 pounds, with the breech. The fired shells weighed between 1,900 and 2,700 pounds. When firing armor-piercing rounds, their muzzle velocity was 2,500 feet per second. When fired at its maximum range of 24 miles, the shell spent almost one minute and 30 seconds in flight.

The turrets were described as “three-gun” rather than “triple” because each gun could be elevated or lowered independently of the others. The battleships could fire any combination of their guns, including a broadside of all nine. From the powder-handling level to the magazines, the projectile handling floor, and the gun deck, each turret required 79 men to staff all four levels.

Project Katie

The origin of the “Katie” shell dates back to 1952, when the world’s first artillery-fired atomic projectile, the MK9, was fired from the 280mm M65 Atomic Cannon, also known as “Atomic Annie.” The M65 cannon and Mk9 shell had a significant drawback: their short range, which was limited to about 14.7 miles.

In 1955, the MK9 was superseded by the introduction of the W19 shell, which weighed a few hundred pounds less, increasing the range to 18 miles. It was also a gun-type nuclear weapon which contained a yield of 15-20 kilotons.

The W19 was quickly modified for use with the Mark 7 guns of the Iowa-class battleships. The W23 was the first nuclear shell designed for a naval gun. It was 16” in diameter, 64” long, and weighed between 1,500 and 1,900 pounds with a 15-20 kiloton yield — the same kiloton range as the Hiroshima and Nagasaki bombs.

If all nine guns fired a salvo, the yield would be approximately 185 kilotons. It is said that the Katie designation came from the abbreviation for kiloton, as in “getting some Kt”.

Under Project Katie, 50 Mark 23 shells were produced for the battleships Iowa (BB-61), New Jersey (BB62) and Wisconsin (BB-64), while the USS Missouri (BB-63) was not modified and left untouched as it was placed into the mothball fleet in 1955. Each battleship carried 10 Mark 23 shells, one for each barrel and one backup round, nine practice shells, and one loading drill round for gunner certifications. The device would be assembled just before firing.

Each ship had modifications made to its “Broadway” section. Broadway is the longest straight passageway on the Iowa-class battleship, with a length of 288 feet between the number II and number III turrets for the safe storage of these shells, and a separate locker for the nuclear warheads, which was secured by a Marine Corps security detachment.

The Katie-armed battleships were short-lived and sent back to the mothball fleet not long after their modifications, and the Mark 23 was completely withdrawn from service by October 1962.

Fortunately, no Mark 23 shell was ever fired in war, but one projectile was expended during Project Plowshare, which studied the use of nuclear weapons for peaceful purposes. There is currently one remaining Mark 23 shell on display at the National Atomic Museum in New Mexico.

The TLAM-N

In the 1980s, the Tomahawk Land Attack Missile (TLAM-N) came into service. The BGM-109A Tomahawk Cruise missile was fitted with a W80 200-kiloton nuclear warhead and had a range of approximately 2,500 kilometers, with a speed of 550 miles per hour. The missile is guided by a combination of GPS, inertial navigation, and Terrain Contour Matching (TERCOM), which compares the missile’s flight path with a stored map of the terrain to navigate. The Tomahawk is estimated to have an accuracy of five meters.

The Tomahawk missile is approximately 20 feet long, with a 21” diameter, and weighs 3,000 pounds. When fired, it begins the launch sequence powered by a solid propellant. When the solid propellant is expended, a turbofan engine takes over and propels the missile to the target. The missile is hard to detect due to its small size, low cross-section, and low heat signature from its turbofan, and it avoids radar by flying at an altitude of only 100 to 300 feet.

Tomahawk missiles, whether conventional or nuclear, were initially launched from the Mark 143 4-cell armored box launcher (ABL) mounted on the deck. The size and weight of the launcher with missiles were prohibitive, as a standard cruiser was only capable of carrying two launchers for a total of 8 missiles. To carry more ordnance, WWII battleships were chosen for their ability to support heavier armaments.

Starting with the USS New Jersey in 1982, all four Iowa-class battleships were modernized and retrofitted for the modern weapons systems, as they were capable of carrying eight box launchers for a total of 32 Tomahawk missiles. Another modification was the addition of the Mark 160 Fire Control system, which was used to guide the Mark 7 16-inch guns.

The box launchers were eventually phased out and replaced starting in 1984 by the Mark 41 Vertical Launch System. The VLS became the standard system installed on U.S. Navy ships, as they were capable of launching Tomahawks, Harpoons, and all other missiles in the Navy’s inventory.

The TLAM-N served as a deterrent for approximately 10 years until 1991, when President George H.W. Bush began removing the nuclear Tomahawks from the Navy’s inventory and putting them in storage. In 2010, the Obama Administration had the inventory dismantled after its Nuclear Posture Review.

The Legacy

U.S. battleships were designed to fight the Axis powers in World War II and were a symbol of U.S. strength. They played crucial roles in the defense of the country, while ushering in the aircraft carrier as the dominant naval power.

With continuous modernization and technological advances, they proudly served well into the nuclear age, while still deploying serious firepower in the old-fashioned way. While never fired in war, the nuclear-armed battleships were a unique deterrent to Soviet aggression during the Cold War.