Britain's Armored Aircraft Carriers: A World War II Super Weapon?

Britain's Armored Aircraft Carriers: A World War II Super Weapon?

The armored decks of the British Illustrious-class aircraft carriers represented a differing philosophy from that of U.S. Navy carrier designers.

Here's What You Need to Know: While they are often overlooked in discussions of the naval war in the Pacific, the Royal Navy’s carriers were very much a part of that conflict as well as the European Theater.

When one thinks of carrier warfare in World War II, the Japanese and U.S. navies usually come to mind. While the two powers were the major proponents of carrier-based aviation as the primary instrument of sea power, the British Royal Navy operated a substantial fleet of aircraft carriers. And while they are often overlooked in discussions of the naval war in the Pacific, the Royal Navy’s carriers were very much a part of that conflict as well as the European Theater.

Request For Carriers With Armored Decks

During the mid-1930s, the British Admiralty asked for a new series of aircraft carriers that would feature armored flight decks configured as integral to the ship’s basic structure instead of being part of their superstructure, as was the practice with U.S. and most other aircraft carrier designs. Whether or not this concept increased the overall survivability of the British carriers is open to debate, but it did reduce the likelihood of aerial bombs penetrating into the depths of the ships.

The design plans for the new carriers were approved in June 1936. The landing decks were to be covered with 3-inch armor plates, while the hangar walls were to be built with armor plating 4 inches thick. The ships’ magazines and their vital machinery were to be protected by a 4-inch armor belt below the waterline. Final design changes included the armored side belt being lengthened forward by 28 feet and aft by 24 feet, the hangar being widened to 62 feet, and the main armament consisting of eight dual 4.5-inch QF MkIII HA guns. This would provide the carriers with a total of 16 4.5-inch guns for antiaircraft and ship defense.

An Illustrious Class Of Carriers

The first of the new armored carriers to be commissioned was HMS Illustrious, on April 5, 1939. It was followed by Formidable, commissioned on August 17, 1939, and Victorious, which was commissioned a month later on September 14. The three armored carriers are sometimes considered to make up the Illustrious class; they were followed by Indomitable, which was very similar in design except that it had two hanger decks and was unique in this regard. Implacable and Indefatigable were also armored carriers, but even though they were very similar to the Illustrious-class carriers, the two ships are often placed into a class by themselves. They were not commissioned until 1942 and did not enter service until the last years of the war. All six carriers were of equal displacement, each at 23,000 tons. They were capable of carrying from 36 to 50 aircraft, depending on the size of the airplanes.

An Historic First Attack Using Biplanes

Upon commissioning, Illustrious was assigned to the Mediterranean Fleet. On November 11, 1940, her planes took part in the first successful carrier raid in military history. Two striking forces made up of 21 Fairey Swordfish torpedo bombers launched from the carrier struck the Italian naval base at Taranto. Already obsolete at the beginning of the war, the Swordfish were single-engine biplanes with a top speed well under 150 knots. Twelve of the slow-moving biplanes were fitted with aerial torpedoes, while the rest were carrying either bombs or illumination flares.

The attack was carried out under the cover of darkness since the slow-moving Swordfish would have been sitting ducks for fighters and antiaircraft in daylight. At anchor inside the harbor lay the pride of the Italian fleet—five battleships, seven cruisers, and 11 destroyers. None of the ships was effectively protected against torpedo attack. The torpedo nets only extended to the depths of the bottom of the battleships, and the British had developed a new type of torpedo that could dive under the nets and explode under the target’s keel. Also in favor of the Swordfish was the fact that many of the barrage balloons that were protecting the harbor had been lost in a recent storm.

Caio To Italian Fleet At Taranto

It was a clear and moonlit night, the kind of night that would later come to be referred to as a “bombers moon.” The pilots could not have asked for more perfect conditions. Six torpedo bombers in the first wave of the attack dropped down to an altitude of only 35 feet and swept into the harbor to focus their attention on the battleships Littorio and Conte di Cavour. Their attack sent the Cavour to the bottom and left Littorio, which was one of Italy’s newest battleships, badly damaged. A second wave of attacking Swordfish inflicted more damage on Littorio and put a torpedo into the side of the battleship Caio Duilio. The attack on the Italian fleet at Taranto resulted in the sinking of one battleship and the crippling of three others, at a cost of two Swordfish lost and two others damaged. The Italian Navy was severely crippled for six months.

With the successful attack on Taranto, Illustrious had earned her place in history. However, within a few months, the new armored carrier found herself the objective of a massive air attack. On January 10, 1941, Illustrious was part of a task force assigned to escort a large convoy of British vessels bound for Greece and the Middle East when she came under air attack. The first attackers, Italian torpedo bombers, were driven off by Fulmar fighters flying from the carrier’s deck. The torpedo bombers proved to be a distraction, drawing British attention away from a large formation of Junkers Ju-87 Stuka dive-bombers and Ju-88 bombers that came in from the north at 12,000 feet. The Stukas screamed down on the carrier.

Illustrious Down But Not Out

Illustrious suffered seven bomb hits from the Stukas and was set on fire. Had it not been for the armored flight deck, the ship would probably have been sunk. As it was, Illustrious was out of the war for several months, undergoing repairs in the United States at the naval shipyards in Norfolk, Virginia. The carrier returned to service in time to provide support for the Allied landings on Madagascar in September 1942. Illustrious was the first British carrier to have search radar installed and the first to have a fighter control officer assigned. With the new equipment and tactics, her planes were credited with the destruction of 75 German and Italian planes within the span of six months.

HMS Formidable also saw action with the Mediterranean Fleet. Only recently commissioned, Formidable had just joined the fleet after sailing through the Suez Canal. The air group on Formidable included a squadron equipped with Fairey Albacore torpedo bombers, which were somewhat faster than the Swordfish. The Albacore’s crew was also protected from the elements by an enclosed cockpit, but the airplane was still lacking by World War II standards.

Formidable in Pitched Battle With Italians

On March 28, 1941, while Illustrious was still in the United States undergoing repair, Formidable played a major role in the Battle of Cape Matapan. Admiral Andrew B. Cunningham, the British commander, attempted to engage the remnants of the Italian Navy with surface vessels, but the British cruisers were slower and not as well armed as those of the Italians. When it appeared that the Italians were getting the best of the British cruisers, Cunningham ordered the launching of a flight of six Albacores. In spite of “friendly fire” aimed at them by sailors who thought they were the enemy and attacks by German fighters, the Albacores pressed on their attack, although with negligible results. Frustrated that the Italians were escaping, Cunningham ordered a second attack, this time by three Albacores and a pair of Swordfish, led by Lt. Cmdr. J. Dalyell-Stead.

In a reversal of the situation that led to the severe damage of Illustrious a few weeks before, the small force of torpedo bombers benefited from a high altitude attack by RAF Blenheim bombers flying from Greece. The bombers diverted the attention of the Italian sailors. When the Italians spotted the low-flying torpedo bombers, a withering fire was directed at the planes, striking the lead aircraft. Lt. Cmdr. Dalyell-Stead, however, managed to release his torpedo before his airplane went into the sea. It struck the Italian battleship Vittorio Veneto and blew a large hole in the ship’s stern, leaving her dead in the water.

German Planes Deliver Crippling Blow To Formidable

Two months later, Formidable herself was attacked by a dozen German dive-bombers near Crete. Although his military commanders advised that the island should be abandoned, British Prime Minister Winston Churchill insisted that it should be defended. After German paratroopers invaded the island, Admiral Cunningham deployed his cruisers and destroyers around Crete while Formidable provided air support from the south. The German Luftwaffe mounted an all-out effort against the British fleet, sinking three cruisers and six destroyers and putting several other capital ships, including Formidable, out of action. Although she escaped the battle, Formidable had suffered major damage in spite of her armored deck. She steamed across the Atlantic to join Illustrious at Norfolk for extensive repairs.