Okinawa and the Ten Go Campaign
In order to achieve maximum success against the American invasion of Okinawa, it was imperative that both the Japanese army and navy cooperate. Although both branches drafted plans for the joint venture, the army plan was adopted. Col. Ichiji Sugita, former Operations Staff Officer at Imperial General Headquarters, would later claim that "the Navy took an extremely negative and indifferent attitude in formulating the Outline of the Operations Plan of the Imperial Army and Navy in January 1945. The new operations plan was formulated with the agreement of the Navy only after enthusiastic suggestion by the Army." This was also the case with the planning for the Ten Go Operation. Capt. Toshikazu Omae, who served as Planning Section Chief, Naval General Staff during that period, later reported:
The actual condition of the Navy's air strength at that time (especially from the viewpoint of training) regrettably would not allow the Navy to participate in the OKINAWA Air Operations which were expected to occur in March or April. The Navy generally desired to avoid the hitherto gradual attrition of semi-trained personnel and did not wish to engage in operations at OKINAWA and other fronts, much less the homeland, until about May, by which time it would have accumulated sufficient fighting strength.
Although both branches of the Japanese military were committed to cooperate against the Americans at Okinawa, the planning ran into problems. Targets to be attacked by the army forces were convoys and troop carriers. These vessels were easier to hit and pilots required less training for the missions. By comparison, the navy targets were the carrier task forces, which were more difficult to attack and required greater flying skills. Japanese navy planning called for additional special attack training. According to Cmdr. Yoshimori Terai, former officer in charge of Air Operations, Naval General Staff, "From the beginning, air preparations (special attack planes) were not expected to be completed until the end of May. Although we desired to delay the American advance on OKINAWA through the Second TAN Operations (attack on ULITHI Base), but as a result of their failure, we were forced to face the Okinawa Operations unprepared."
The situation was no better for the army. With the failure of the operations against Ulithi and the accelerated advance of the American forces toward Okinawa, the army was caught in the time trap as well. According to Japanese naval officers involved in the planning for Ten Go, "the preparations of the 6 Air Army were even more behind schedule than those of the Navy." Still, cooperation between the branches was necessary. Navy Directive No. 540 of 1 March 1945 detailed the extent of that cooperation.
The Army-Navy Joint Central Agreement on Air Operations
1. Policy To destroy the enemy, who is expected to invade the East China Sea and the vicinity, with a display of the combined air strength of the Army and the Navy and at the same time to strengthen the direct Homeland defense. In order to execute the above-mentioned operations, emphasis will be placed on build-up and use of the special attack strength.
2. The principle of air operational guidance in each area:
a. Air operations in the East China Sea and the vicinity (Formosa, the Nansei Islands, Southeast China, Kyushu and Korea).
b. The Army-Navy air forces will immediately deploy in the East China Sea and the vicinity and destroy enemy invading units.
c. The chief targets for the Navy air forces will be enemy carrier striking task forces, and for the Army, enemy transport convoys. However, the Army will cooperate as much as possible in the attack against enemy carrier striking task forces.
Navy Directive No. 513, issued by Adm. Koshiro Oikawa on 20 March 1945, spelled out the goals of the Ten Go Operation. Its first priority was the destruction of the American carrier task forces that had been attacking Japan. This was to be accomplished by the mass use of kamikaze aircraft, suicide boats, manned torpedoes, and midget submarines. A secondary target was the American invasion fleet operating in and around Okinawa. Of particular importance were the air bases on Okinawa. Should they fall into American hands, the security of the home islands would be further imperiled.