Japanese Aircraft Carrier Kaga - Early Service and Development of Carrier Doctrine

Early Service and Development of Carrier Doctrine

On 1 December 1931 Kaga was assigned as the flagship of the First Carrier Division under the command of Rear Admiral Takayoshi Katō. The First Carrier Division, along with Hōshō, departed for Chinese waters on 29 January 1932 to support Imperial Japanese Army troops during the Shanghai Incident as part of the IJN's 3rd Fleet. The B1M3s carried by Kaga and Hōshō were the main bombers used during the brief combat over Shanghai.

Kaga's aircraft, operating from both the carrier and a temporary base at Kunda Airfield in Shanghai, flew missions in support of Japanese ground forces throughout February 1932. During one of these missions three of Kaga's Nakajima A1N2 fighters, including one piloted by future ace Toshio Kuroiwa, escorting three Mitsubishi B1M3 torpedo bombers, scored the IJN's first air-to-air combat victory on 22 February when they shot down a Boeing P-12 flown by an American volunteer pilot. Kaga returned to home waters upon the declaration of the cease-fire on 3 March and resumed fleet training with the rest of the Combined Fleet.

At this time, the IJN's developing carrier doctrine was still in its earliest stages. Kaga and the IJN's other carriers were initially given roles as tactical force multipliers supporting the fleets's battleships in the IJN's "decisive battle" doctrine. In this role, Kaga's aircraft were to attack enemy battleships with bombs and torpedoes. Aerial strikes against enemy carriers were later, beginning around 1932–1933, deemed of equal importance in order to establish air superiority during the initial stages of battle. The essential component in this strategy was that the Japanese carrier aircraft must be able to strike first with a massed, pre-emptive aerial attack. As a result, in fleet training exercises the carriers began to operate together in front of or with the main battle line. The new strategy emphasized maximum speed from both the carriers and the aircraft they carried as well as larger aircraft with greater range. Thus, longer flight decks on the carriers were required in order to handle the newer, heavier aircraft which were entering service.

Kaga was soon judged inferior to Akagi because of her slower speed, smaller flight deck (64 feet (19.5 m) shorter), and problematic funnel arrangement. Because of Kaga's perceived limitations, she was given priority over Akagi for modernization. Kaga was relegated to reserve status on 20 October 1933 to begin a second major reconstruction, with an official start date of 25 June 1934.