JR Potts, AUS 173d AB (Updated: 3/12/2015):
The IJN Zuikaku measured a running length of 844.81 feet (257.5m) with a beam of 91.86 feet (28m) wide and a draught of 29.19 feet (8.9m). The vessel displaced at 25,675 tons under a standard load and some 32,105 tons when heavy. Her top listed speed was approximately 34.2 knots thanks to the Geared Steam Turbine engines powered by 8 x Kanpon brand boilers producing 165,000 shaft horsepower to her 4 x shafts, each capped with five-bladed propellers. Before requiring refueling, the Zuikaku could steam out to 9,700 nautical miles at 18.
The standard operating crew of the Zuikaku generally comprised up to 1,660 officers and sailors. Her island was set to the starboard side of the flight deck and was relatively forward and small compared to her contemporaries. For aircraft and ship defense she was built with 16 x 5-inch 40 caliber dual-mounted cannons as well as 36 x 25mm dual-mounted antiaircraft guns. This served the vessel well in providing a network of guns to help protect the rather vulnerable carrier should she be found without her own fleet for protection. To counter small naval mines, her belt armor ranged from 1.8 inches to 6.5 inches in thickness however this left little in the way of protection against all manner of torpedoes. Her primary purpose was to carry aircraft into battle and, as such, the Zuikaku fielded up to 27 x Aichi D3A "Val" dive bombers, 27 x Nakajima B5N2 Model 12 "Kate" torpedo bombers and 18 x Mitsubishi A6M "Zero" fighters. The ship had room for the 72 aircraft with a reserve store of 12 additional aircraft for a grand total of 84 aircraft. By any regard, the Zuikaku could field a rather lethal array of fighting aircraft against any manner of foe.
In 1941, the Zuikaku was staffed with a trained crew, experienced naval pilots and capable maintenance personnel and further stocked with some of the then-best fighting aircraft anywhere in the world. She was ready to be assigned and was chosen, along with three other carriers, to join IJN Carrier Division 5 as part of the Kido Butai (Mobile Force) staging in Hittokapu Bay, Japan. This group was waiting for their sailing orders to attack the US naval facilities and fleet stationed at Pearl Harbor, Hawaii. The main prize was to knock out the American carrier force which presented a significant threat to ongoing Japanese expansion across the Pacific. For the Hawaii operation, the IJN assigned additional crew and placed onboard a further 12 disassembled spare aircraft of each type. The order came down and the battle force sailed towards Pearl on November 26th,1941. The US Navy was aware of the ship's movements based on reports from their own submarine actions in the area. However, contact was eventually lost with the groups and the Japanese naval attack force followed a secret route believed to be relatively safe from prying eyes. The route did prove successful and the carriers of Kido Butai launched their attack aircraft on December 7th, 1941.
Zuikaku launched her first wave, comprised of 25 dive bombers, and attacked the US Army airbase at Wheeler Field on the island of Oahu. Five Zeros lent their ferocity to attacking the airbase at Kaneohe. Her aircraft of the second wave consisted of 27 Kate torpedo bombers, these armed with bombs instead of their torpedo ordnance, and attacked the US Navy airbase at Hickam Field. A further 17 dive bombers struck the battleships USS Maryland and USS California who were moored at "Battleship Row" in Pearl Harbor proper. Maryland was damaged from the attacks but managed to survive. However, California was sunk by the attacking aircraft. After the second wave was retrieved back on the decks of the Zuikaku, it was determined that the American carrier force was not present at the harbor as intended. It was this fear of the missing carrier group that forced the IJN Mobile Force to withdraw and return to Japanese waters before further attacks could be carried out. Nevertheless, the United States formally declared war on the Empire of Japan to which the Japanese Empire returned the declaration - prompting Germany and Italy to join the Japanese side.
With the United States officially in the war by January of 1942, Zuikaku and her sister ship were sent to the South Pacific to assist in attacking Australian bases at Rabaul and Lae in New Guinea. The vessels returned to Japan for refitting and, in April of 1942,they formed the critical air wing of a IJN force sent to counter the British Navy in the Indian Ocean. The first step was to attack the British naval bases at Colombo and Trincomalee on Ceylon. IJN surface ships shelled the bases while the carrier aircraft bombed ships stuck in the harbor and in the surrounding ocean. The British Royal Navy aircraft carrier HMS Hermes and the heavy cruisers HMS Cornwall and HMS Dorsetshire were sunk along with other support ships. The sinking of an aircraft carrier and two capital ships and others by the aircraft of Zuikaku and her sister ship surpassed the all of the tonnage sunk during their assignment during the attack on Pearl Harbor.
In May of 1942, the IJN developed "Operation Mo" the invasion of Port Moresby, New Guinea. Ownership of the port would ensure a embarkation point for Japanese Army troops to support the future invasion of the Australian mainland. Zuikaku was assigned, again with her sister ship, to support the landings against possible Allied interference. The US Navy decrypted Japanese naval messages and dispatched the aircraft carriers USS Yorktown and USS Lexington to counter the invasion. The upcoming battle on May 8th, 1942, would be called the "Battle of the Coral Sea".
Zuikaku escaped visual detection from US Navy spotter aircraft by hiding under a passing rain squall, but her sister ship - Shokaku - was struck by three bombs, knocking out a flight deck elevator and damaging the flight deck to the point that launching and recovering planes was impossible. Aircraft from both carriers and torpedoes from IJN escorting destroyers sank the carrier USS Lexington. Zuikaku was undamaged but lost one fighter aircraft, eight dive-bombers, and fourteen torpedo planes including losses of fourteen pilots and applicable crew. She was then ordered to return to Japan with her sister for resupply and aircrew training. The loss of carrier air cover blunted the attack on Port Moresby and the damage to the carriers and loss of trained crews made both carriers unable to take part in the upcoming Battle of Midway in June 1942 - what turned out to be a decisive Allied victory in the Pacific.
In August of 1942 the US Navy was now on the offensive in the Solomon Islands. Zuikaku and the repaired Shokaku, supported by the light carrier Zuihonow, were assigned to Carrier Division One and ordered to sail forward to destroy the Americans. On August 24th, 1942, the Battle of the Eastern Solomons began and Zuikaku's airwing damaged the carrier USS Enterprise, who in turn was damaged by American carrier planes. After the battle - registered as another Allied victory - Zuikaku was sent to Truk to monitor allied naval activity in the area.