The Loss of Japan's 'Unsinkable' Fleet Changed The Course of World War II In the Pacific

At the outset of World War II, the Imperial Japanese Army (IJA) and Navy (IJN) appeared invincible. Their personnel exhibited extraordinary bravery and a willingness to lay down their lives for their mission, while their leaders were viewed as cunning tacticians. A key aspect of the Japanese strategy was the deployment of aircraft carriers to support and protect their pilots.

Therefore, the most efficient way to overcome them was to focus on and eliminate these ships.

Japanese aircraft carrier Kaga

Commissioned in 1921 following construction that began the previous year, Kaga was originally planned as a battleship of the Tosa- class. However, with the adoption of the Washington Naval Treaty in 1922, which allowed for the conversion of two battleship into aircraft carriers , Kaga was designated for scrapping. The Great Kantō earthquake of 1923 caused the loss of the battlecruiser Amagi , prompting a decision to convert Kaga instead of Amagi .

Kaga 's transformation involved modifying her flight deck into three superimposed decks and making other necessary alterations. Additionally, she was equipped with a twin-gun Model B turret on each side of the middle flight deck and six casemate-mounted guns aft, along with 10 Third Year type 20 cm/50 caliber guns, previously used as the primary armament for Japan's heavy cruisers during WWII .

Following successful sea trials, Kaga was formally commissioned into the Imperial Japanese Navy as its third aircraft carrier in November 1929, joining Akagi and Hōshō in the fleet.

Kaga 's early service with the Imperial Japanese Navy

Kaga was swiftly put into action after her completion, joining the Navy's 3rd Fleet to support the Imperial Japanese Army during the Shanghai Incident in 1932. The bombers aiding the Japanese ground forces at that time were launched from Kaga and the aircraft carrier Hōshō .

After the Shanghai Incident, Kaga underwent multiple modifications, as she was considered the weaker carrier in the Imperial Japanese Navy's fleet. She was then deployed during the 1937-45 Second Sino-Japanese War , where Japan once again clashed with China. Kaga remained in Japanese waters, serving as the base of operations for aircraft on bombing missions.

The conflict ultimately ended unfavorably for the Japanese forces, who surrendered to the Chinese and relinquished the previously captured territory.

Japanese attack on Pearl Harbor

In 1941, the Japanese Imperial Army tasked Marshal Admiral Isoroku Yamamoto with planning a large-scale offensive against the US Navy 's Pacific Fleet . This wound up being the December 7 attack on Pearl Harbor , in which Kaga played a role. For the attack, the aircraft carrier had ferried 18 Mitsubishi A6M Zeros , 27 Nakajima B5Ns and 27 Aichi D3As.

The bombers and fighters that took off from Kaga were successful in their missions, scoring hits on the USS Maryland (BB-46), West Virginia (BB-48), Oklahoma (BB-37), Nevada (BB-36), California (BB-44) and Arizona (BB-39). In addition, they destroyed 20 grounded American aircraft and took out a single airborne one.

Once her mission at Pearl Harbor was complete, Kaga returned to Japan. Her work in the Pacific Theater, however, was far from over.

Kaga 's continued World War II service

Following the attack on Pearl Harbor, Kaga was moved to Truk, in Micronesia. From there, she supported the Battle of Rabaul , providing aircraft for the initial airstrike. In February 1942, her aircraft took part in a sortie against an American battleship in the Marshall Islands . During the effort, she ran into a reef and had to be temporarily removed from service for repairs, before returning to duty.

Kaga 's final engagement was during the Battle of Midway . She departed from the Inland Sea at the end of May 1942, along with the rest of the Combined Fleet, and set up around 290 miles northwest of Midway Island.

On June 4, 1942, the ship was relentlessly attacked by American dive bombers. The first attempt was initially repelled by the Japanese, while the second, led by US Navy aviator C. Wade McClusky, was much more successful. Twenty-five Douglas SBD Dauntless from the USS Enterprise (CV-6) appeared over the ship, nearly undetected, and hit Kaga with a 1,000-pound bomb and multiple 500-pound bombs.

After failed attempts to repair the damage, the aircraft carrier sunk into the Pacific Ocean.

Aftermath of the Battle of Midway

While some sailors were rescued from Kaga , a large number perished; 811 of those aboard the vessel, many of them engineers, armorers and mechanics, were killed. That's not to mention the number of pilots who lost their lives. Government and military officials, focused on looking invincible, were worried about news reaching the Japanese public, and the surviving sailors were snuck back into the country to prevent Midway's story from getting out.

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The battle, itself, is seen as a turning point in the Pacific Theater. In addition to Kaga , the Imperial Japanese Navy lost three other aircraft carriers: Akagi , Sōryū and Hiryū . The loss of the vessels and the aviators who manned their aircraft significantly impacted Japan's effectiveness, and the country's forces were never able to recover. For many, it's one of the major contributing factors for its defeat in the war.