IJN Nagato Class Battleships
The Nagato was the first Japanese battleship to be designed domestically, as well as the first battleship built with 16 inch guns. She was designed by Captain Hiraga Yuzuru of the Imperial Navy in the first part of 1916 and by Japanese accounts placing her several months of the USS Maryland, an American ship of similiar capability. The battleship Nagato was built by Kure Navy Yard for the Imperial Japanese Navy under provision of the 1916-1917 Program of Naval Construction by that nation. The Nagato was laid down on 28 August 1917 at the Kure Naval Yard, Nagato was launched on November 9, 1919 and completed over three years later on 25 November 1920.
The Nagato and her sister ship, Mutsu, were built with speed in mind and were very similiar to the British Queen Elizabeth class battleships in this regard. In sea trials in 1920, the Nagato clocked in at 26.7kts, a blistering speed at the time for battleships. In regard to armor, the Nagato class resembled the American "All or Nothing" practice in regard to naval armor. That is, due to shell technology in which shells exploded after breaching thin armor, it was deemed better to replace it with either very heavy armor or none at all. Despite adhering to the practice, the Nagato's Japanese designers did not feel comfortable without adding armor to the lower deck, something not found on American ships. A particular detail of the armor arrangement involved protection of the torpedo bulkhead which was sloped out to meet the armor deck, and provided complete protection. The design was later incorporated into all future capital ships.
The Nagato class were also equipped with the identifable heptapodal mast unique to Japanese ships. These masts consisted of one thick vertical mast in the center with two legs which sloped forward towards their perspective beam, port or starboard. Inteference from smoke was also a problem for the masts, which were placed close to the funnels. As a result, the funnels were equipped with smokehoods shortly after test trials were completed.
Like many ships in the Imperial Navy, the Nagato and the Mutsu underwent reconstruction in the mid 1930's for modernization. These modifications included increasing the elevation of the main battery to 43 degrees for a range increase of 8,000 meters. Both ships also received more armor in the areas of gun turrets, barbettes, and deck protection over the machinery. In total, the ships received an additional 2,600 tons of armor. Their machinery was refurbished, but not replaced, unlike other ships in the time period going through similiar reconstructions. Between 1934-1936, Nagato was reconstructed: torpedo bulges were added and the superstructure was raised and modified. The battleship was originally coal-fired; between 1934-1936 the ship's machinery was replaced with new oil-burning boilers. This led to the removal of Nagato's forward stack. During the reconstruction, in addition to new machinery and torpedo bulges, Nagato received a triple bottom, additional deck armor, and increased elevation for the 16-inch guns.
The Japanese battleship Nagato was a steel-hulled vessel 708 feet in length overall, with a 95-foot beam and a 30-foot draft. Nagato displaced 38,500 tons standard. The ship was armored with a 3.9-to-11.8-inch belt; the turrets were protected by 14-inch thick armor. Nagato's armament consisted of eight 16.1-inch/45 caliber guns, twenty 5.5-inch/50 caliber guns, four 3.1-inch antiaircraft guns, three machine guns, and eight 21-inch torpedo tubes, four above and four below the waterline. In June 1944, Nagato had sixty-eight 25mm Hotchkiss antiaircraft guns; by October of the same year, the number of antiaircraft guns had increased to include ninety-eight 20mm guns. At that time, Nagato retained eighteen 5.5-inch guns; Nagato's full load displacement at that time was 43,581 tons.
Nagato's four screws were driven by Gihon steam turbines that developed 80,000 shaft horsepower at 26.7 knots. By October 1944, the rated speed of the vessel was 24.98 knots. Steam was provided by 21 Kanpon boilers. Nagato carried three observation planes launched by catapult forward of the "C" turret. According to the U.S. Navy's confidential report on the Japanese Navy, ONI-221-J, issued in June 1945, "the most outstanding outboard feature of Nagato is the large heptapodal foremast with its numerous tops and bridges for fire and ship control purposes. The central vertical leg is thick enough to accommodate an electric lift running between the foretop and main deck." Nagato's hull was reportedly divided into 560 separate watertight compartments; its rated complement was 1,333 men.
Both ships were operated during the Second World War, but only the Nagato survived. Nagato served in its most famous role as flagship for Adm. Isoroku Yamamoto, Commander in Chief for the Combined Fleet. Nagato, "its entire crew manning the sides," led the combined fleet in its last official public display on October 11, 1940, during an Imperial review off Yokohama in ceremonies celebrating the 2,600th anniversary of the accession of Jimmu, Japan's first emperor.
Nagato was the scene of Yamamoto and his staff as many meetings by plans to attack the U.S. Pacific Fleet at Pearl Harbor were first broached, discussed, and refined. Final preparations for the war were made aboard Nagato, and Yamamoto stood aboard Nagato with the battleship's crew as the Pearl Harbor strike force vessels sortied. With them the Japanese aircraft carriers brought specially modified 16-inch shells from Nagato and its sister Mutsu that would be dropped on the American ships at Pearl Harbor as bombs. One of these shells would be credited with sinking the battleship Arizona. Nagato was the scene of nervous waiting by Yamamoto and his staff. They first heard of Japan's overwhelming success at Pearl Harbor when Nagato's radio operator received the famous "to, to, to" signal for a successful attack's commencement--crystal-clear reception from the skies over Oahu thousands of miles away.
Nagato served as flagship for Yamamoto until replaced by the 63,700-ton super battleship Yamato in February 1942. Yamamoto, when he shifted his flag to Yamato, released the older battleship for operational duty; thus, Nagato as part of the Japanese Main Force steamed with the striking force that attempted to take Midway and the Aleutians in late May 1942. Nagato, however, was not engaged in combat in the disastrous engagement off Midway in June in which four carriers were sunk by American carrier aircraft.
Nagato next sortied with the fleet in the Marianas in June 1944. This disastrous battle, Japan's last opportunity to win a decisive naval engagement, ended in defeat and the withdrawal of the fleet to Japanese home waters. The fleet, with Nagato, again sailed in October 1944 to engage the American fleet at the Battle of Leyte Gulf. Nagato, in formation with the super battleships Musashi (sunk in this engagement) and Yamato, was hit by two torpedoes but survived, assisting Yamato off Samar. In retreat Nagato took a heavy pounding from carrier bombers; it was hit by four bombs and was damaged by nine near-misses. Upon reaching Japan, Nagato was left at anchor at Yokosuka, awaiting repairs that never came. Thus, the crippled Nagato, tied up at Yokosuka, missed the last sortie of the Imperial Japanese Navy in April 1945. In that special kikusui (battle of certain death) Yamato was sunk, effectively destroying the Imperial Japanese Navy as a fighting force.
Nagato, already badly damaged, was again mauled by aerial attack while at anchor at Yokosuka on July 18, 1945. The principal target of the attack, Nagato was moored close to shore next to antiaircraft batteries and camouflaged by the removal of its mainmast and stack. The battleship was pounded by aircraft from USS Yorktown (CV-10). Nagato was neutralized--the bridge wrecked, and the decks and superstructure holed and damaged. Ending the war out of action in Tokyo Bay, Nagato was the only Japanese battleship to survive the war afloat. Following the Japanese surrender, Task Force Thirty-One (the Tokyo Bay occupation force) landed and occupied the Tokyo Bay area. Navy Underwater Demolition Team 18 was assigned to "capture" Nagato on August 30, 1945. This act, according to the U.S. Navy, "symbolized the unconditional and complete surrender of the Japanese Navy."
The Mutsu was sunk, not by Allied efforts, but from an internal explosion (her magazine the most likely source) which sent her to the bottom of the Inland Sea. The Nagato was taken by the United States as a war prize and was used by the Navy to test the affects of an atomic bomb detonation on a surface fleet at the Bikini Atoll.
Unlike some other captured vessels, Nagato was not brought into the U.S. Navy as a special auxiliary, as was the case with the German battle cruiser Prinz Eugen. This may have been because Nagato was heavily damaged and was of no use to the United States as a capital ship. The vessel was also a symbolically laden ship, being the "flagship" of the kido butai or "strike force," as well as the genesis point of the plan for the attack on Pearl Harbor, which Americans perceived as a vicious sneak attack, and onetime quarters of Yamamoto, who, while a villain in the United States was still very much a hero to the Japanese. Nagato, not surprisingly, was selected as a target vessel for Operation Crossroads. In early 1946 the ship was prepared at the Yokosuka Naval Base and steamed under its own power close to Bikini Atoll in the company of the captured cruiser HIJMS Sakawa.
Nagato's imminent arrival was noted in "Crossroads," the semi-official newsletter of the tests, on April 27, 1946: "Once the lofty pride of the Japanese fleet, the battleship Nagato will strike an ironic contrast as she enters the atoll shortly. Flying the American ensign and manned by an American crew, she will be the first of the 'guinea' ships to take her position for what may well be her last mooring. Then, humbly, she will await the fateful day when the blow, mightier than the greatest salvo ever produced by man, will descend." After its arrival at the end of April, Nagato, "the one-time pride of the Japanese Navy," was eagerly explored by sightseeing sailors. According to the May 4 edition of "Crossroads," "this huge battleship appears to have already undergone the blast. Visitors will find that she is pretty-well shattered, her decks and bulkheads rusty, and her equipment highly picked over. An LST alongside supplies all her water and electricity." The vessel was prepared by a repair ship for the tests at Bikini, and then moored 400 yards to the starboard of Nevada, target ship for the Able test. When the bomb missed Nevada, Nagato was only moderately damaged by the Able blast; light plating on the superstructure was wrinkled and light non-watertight doors were blown off their hinges; paint was scorched. The report on the ship concluded that "the Nagato is structurally sound.... The poor condition of the ship and her equipment is due to lack of preventive maintenance and overhaul, and to the fact that her engineering plant sat idle for over a year."
She survived the intitial air burst test and remained afloat for five days following an underwater blast before finally succumbing to massive hull damage and sinking. The end came for Nagato when the Baker test bomb detonated nearby on July 25, 1946.  The passing of the battleship under these circumstances made a profound impression on the Japanese. Naval historian Masanori Ito wrote: "When World War II began, the Japanese Navy--the third most powerful in the world--included some of the mightiest ships in naval history and was a force worthy of the pride and trust of the Japanese people. Then, in less than four years, this great war machine fell from glory to oblivion. Of ten battleships riding in Hiroshima Bay in December 1941, nine were sunk. The lone survivor, Nagato, died at Bikini Island as a target in an atomic bomb test."
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