World War 1 (1914-1918) spurred many-a-nation to bulk up their naval power and this included the Japanese Empire. A major ship-building program ensued which sought to provide the fleet with a strong collection of battleship and cruiser types heading into the next decade. The Dreadnought battleship, brought about by the British commissioning of HMS Dreadnought in 1906, was still the warship of the day and to this standard was applied to the new Japanese battleships to come. However, the Japanese plan was derailed some following the end of the war in 1918 for, in 1922, the Washington Naval Treaty was signed to help limit a potential new arms race through warship design restrictions. Japan served as one of the cosigners, joining the United States, Britain, and France among others. This ultimately meant that only two of the proposed batch of new warships would be completed - these becoming IJN Nagato and IJN Mutsu of the two-strong Nagato-class.
IJN Nagato was laid down on November 15th, 1920 by the Kure Naval Arsenal and launched on November 9th, 1919 - her namesake being the Nagato Province in Southwest Japan. The vessel was formally commissioned on November 25th, 1920 to begin a career that would last until the end of World War 2 (1939-1945) though her sister would meet her fate in June of 1943.
As built, Nagato displaced 32,720 tons (standard) and held a length of 708 feet, a beam of 95.2 feet, and a draught of 29.8 feet. Her machinery was made up of 21 x water-tube boilers feeding 4 x steam turbines driving 4 x shafts at 80,000 horsepower output. Maximum speed was 26.5 knots with a range out to 6,300 miles. Twin smoke funnels made up her profile as did a forward and aft mast structure. Armor ranged from 305mm thickness at the belt to 369mm at the conning tower. Her standard crew arrangement numbered 1,333 personnel. A single launching catapult was carried to support up to three floatplane aircraft for over-the-reconnaissance work and limited aerial bombing duties.
Armament was made up of 8 x 16" (410mm) guns set across four primary turrets - tow held fore and two held aft. The installation of 16" guns on this warship (and her sister) were the largest main guns ever fitted to a capital ship. 20 x 140mm Dual-Purpose (DP) guns made up the secondary armament and these were fitted as single-gunned turrets. 4 x 76mm guns in single-gunned mounts made up the Anti-Aircraft (AA) armament arrangement. As was the case with most surface ships of the period, Nagato also carried torpedo armament through 8 x 533mm (21") tubes.
All told, Nagato - and her sister ship Mutsu - outclassed all other vessels of the day when they were formally commissioned in the early 1920s, making them some of the more powerful naval assets to available to any one country. They possessed the perfect blend of speed, armor, and firepower to make them immediately noticeable on the world stage. One of her first commitments was as flagship of the 1st Battleship Division and, following the Great Kanto earthquake of 1923, she served in the humanitarian role. In the middle of the decade, some of her design was modernized to keep the warship a viable instrument of war with the changing times (Japanese engineering prowess was also advancing during this particular period). In the early 1930s, her AA defense network was reworked for the better and, from the period of 1934 to 1936, the vessel was given much more major attention: her hull was widened to provide for better sea keeping, she lost her forward smoke funnel, and the forward mast was integrated to the new pagoda-style bridge arrangement. Beyond obvious changes to her profile, she was also the recipient of additional armor protection though this at the expense of speed. The loss of speed was mitigated some by the installation of new boiler units though her turbines remained unchanged from their original fittings. All of the changes led to an increase in displacement of the vessel - though by World War 2, the Washington Naval Treaty was hardly honored let along enforceable.
With the work completed, Nagato formed up with the 1st Battleship Division as part of the 1st Fleet and went on to support government forces in Tokyo Bay during a limited, Army-led coup during February 1936. She then supported Army forces during the Second Sino-Japanese War (1937-1945) and this preceded a period of gunnery training. She was promoted to flagship of the Combined Fleet in December of 1938 and took part in the October 1940 celebrations marking the 2,600th anniversary of Emperor Jimmu's (711 BC - 585 BC) enthronement.
In December of 1941, Admiral Isoroku Yamamoto (1884-1943) used Nagato as his flagship during the Japanese surprise attack on Pearl Harbor, Hawaii (December 7th, 1941). The attack was an attempt to destroy the American Pacific Fleet and provide freer range of Japanese elements throughout the Pacific Theater. Despite the stellar success of the attack, the operation was a failure in that the American carriers were out of harbor at the time. The Japanese Navy claimed several enemy warships, support ships, aircraft, and depots in the assault but little else.
IJN Nagato was brought back to the Kure Naval Yard from March to April 1942 and underwent a needed refit. Her next call to action was during the Battle of Midway (June 1942) as part of Battleship Division One, serving alongside the storied IJN Yamato. The battle was disastrous for the Japanese as four aircraft carriers were sunk to the enemy's one and 248 aircraft lost to the American's 150. The battle claimed the lives of 3,057 Japanese to the American total of 307. Nagato was then transferred to Battleship Division 2 and served as flagship of the 1st Fleet. In August of 1942, Nagato supported the Solomon Islands campaign and another period of training followed which led her into 1943.
Much of her service in 1943 was in the southwest Pacific region and revealed little action. She arrived near Singapore in February of 1944 and again served as flagship until May. She saw a refit around this time and was sent to Tawitawi for May 12th as part of the 1st Mobile Fleet. Her next call to action was as escort during the Battle of the Philippine Sea (June 1944). Again, the results were contrary to Japanese hopes as the Americans claimed another decisive victory. The air portion of the battle came to be known as the "Great Marianas Turkey Shoot" for some 550 to 645 Japanese planes were downed. Three more Japanese carriers were sunk and nearly 3,000 men perished in the fighting.
Nagato made her way to Kure where she was fitted with new radar and improved AA facilities. She took an infantry division to help strengthen Okinawa for July and, during the Battle of Leyte Gulf, served with Admiral Takeo Kurita's strike force to head off American amphibious landings in the Philippines Campaign. Her commitment ended in October.
On October 24th, Nagato came under fire from American dive bombers which left her severely damaged. Temporary repairs took hold and allowed her to see action off of Samar (October 25th 1945) where she served alongside IJN Yamato once more. The battle proved another American victory.
IJN Nagato was the unfortunate recipient of more American bombs which damaged her only lightly but forced her into retreat with other Japanese naval forces. On November 15th, she was made part of Battleship Division 3, 2nd Fleet and left for Kure shortly thereafter. She arrived at Yokosuka on November 25 for much-needed repair work. However, materials were in such short supply that the vessel was retained as a floating Anti-Aircraft platform to counter the increasing threat of American aircraft over the Japanese mainland. For her new role, she was heavily modified as many of her obstructions were removed and more AA guns added. She came under reserve status on April 20th, 1945.
Her last notable action in the conflict occurred during June when she was assailed by American warplanes. Though damaged, she survived and sat where she was attacked until the end of the war on August 15th. The vessel was then claimed by the Allies a few weeks later and her name struck from the Naval Register on September 15th - this ending her formal service to the Japanese Navy. Once in American hands, the warship stood as part of the nuclear weapons testing (Operation Crossroads) at the Bikini Atoll in 1946. She was sunk as a target on July 25th, 1946.