Japanese Aircraft Carrier Kaga - Sino-Japanese War

Sino-Japanese War

Kaga returned to service in 1935 and was assigned to the Second Carrier Division. The carrier embarked a new set of aircraft, including 16 Nakajima A2N Type 90 fighters, 16 Aichi D1A Type 94 dive bombers, and 28 Mitsubishi B2M Type 89 torpedo bombers.

The renewal of hostilities with China at the Marco Polo Bridge in July 1937 found Kaga in home waters. The ship's fighter squadron completed training at Ōmura, Nagasaki then helped escort ships taking army reinforcements from Japan to China. On 15 August, along with Hōshō and Ryūjō, the ship took station in the East China Sea as part of the 3rd Fleet and began supporting Japanese military operations along the central China coast around Shanghai and further inland.

Kaga aircraft fought their first battle on 16 August 1937 when six Type 90 fighters engaged four Chinese aircraft over Kiangwan, shooting down three without loss. Between 17 August and 7 September, Kaga's Type 90 and two Mitsubishi A5M Type 96 fighters, which joined the carrier on 22 August, engaged Chinese aircraft on several more occasions. Kaga's fighter pilots claimed to have shot down 10 Chinese aircraft in these encounters without loss. On 17 August twelve of the carrier's bombers attacked Hangchow without fighter escort and 11 of them were shot down by Chinese fighters. Beginning on 15 September, six Type 90 and six Type 96 fighters, 18 dive bombers, and 18 torpedo bombers were temporarily deployed to Kunda Airfield from the ship to support land operations.

On 26 September the carrier went to Sasebo for reprovisioning. At Sasebo, the carrier received new replacement aircraft including 32 Yokosuka B4Y Type 96 carrier attack planes (torpedo bombers), 16 Aichi D1A2 Type 96 carrier bombers (dive bombers), and 16 more Type 96 fighters. Several Nakajima A4N Type 95 fighter aircraft augmented the carrier's fighter group at an unspecified later date.

Kaga returned to the front in early October 1937, and except for two brief trips to Sasebo, remained off China until December 1938. Using Taiwan (then part of the Empire of Japan) as its base, the carrier steamed 29,048 nautical miles (53,797 km; 33,428 mi) supporting military operations from the South and East China Seas. During that time, Kaga bombers supported army operations by attacking enemy railroad bridges, airfields, and transportation vehicles. The carrier's fighter pilots claimed to have destroyed at least 17 Chinese aircraft in aerial combat while losing five aircraft themselves. On 12 December 1937 Kaga aircraft participated in the Panay incident.

Kaga entered the shipyard on 15 December 1938, where her arrester gear was replaced by a Type 3 system and her bridge was modernized. The flight deck and hangar areas were enlarged, increasing the carrier's aircraft capacity. The ship was completely overhauled from 15 November 1939 to 15 November 1940 before returning to active service. In the meantime, a new generation of aircraft had entered service and Kaga embarked 12 Mitsubishi A5M fighters, 24 Aichi D1A dive bombers and 36 Yokosuka B4Y torpedo bombers. Another 18 aircraft were carried in crates as spares.

The Japanese carriers' experiences off China had helped further develop the IJN's carrier doctrine. One lesson learned in China was the importance of concentration and mass in projecting naval air power ashore. Therefore, in April 1941 the IJN formed the First Air Fleet to combine all of its fleet carriers under a single command. On 10 April 1941 Kaga was assigned to the First Carrier Division with Akagi as part of the new carrier fleet, which also included the Second and Fifth carrier divisions. The IJN centered its doctrine on air strikes that combined the air groups within carrier divisions, rather than each individual carrier. When more than one carrier division was operating together, the divisions' air groups were combined with each other. This doctrine of combined, massed, carrier air attack groups was the most advanced of its kind of all the world's navies. The IJN, however, remained concerned that concentrating all of its carriers together would render them vulnerable to being wiped out all at once by a massive enemy air or surface strike. Thus, the IJN developed a compromise solution in which the fleet carriers would operate closely together within their carrier divisions but the divisions themselves would operate in loose rectangular formations, with approximately 7,000 metres (7,700 yd) separating the carriers from each other.

Although the concentration of so many fleet carriers into a single unit was a new and revolutionary offensive strategic concept, the First Air Fleet suffered from several defensive deficiencies which gave it, in Mark Peattie's words, a "'glass jaw': it could throw a punch but couldn't take one." Japanese carrier anti-aircraft guns and associated fire control systems had several design and configuration deficiencies which limited their effectiveness. Also, the IJN's fleet combat air patrol (CAP) consisted of too few fighter aircraft and was hampered by an inadequate early warning system, including a lack of radar. In addition, poor radio communications with the fighter aircraft inhibited effective command and control of the CAP. Furthermore, the carriers' escorting warships were not trained or deployed to provide close anti-aircraft support. These deficiencies, combined with the shipboard weaknesses previously detailed, would eventually doom Kaga and other First Air Fleet carriers.