This was a Japanese reinforcement convoy to the Doberai peninsula of the Vogelkop at the western end of Japanese-occupied Netherlands New Guinea (17 April/9 May 1944).
In September 1943 the Japanese navy and army had agreed to establish defensive positions along what was termed the ‘absolute zone of national defence’ with a perimeter extending in the north-east from the Mariana islands group via the Caroline islands group to western New Guinea and the Banda and Flores Seas in the south-west. At this time there were few army units in these forward defensive areas, so the decision was taken to move combat formations and units from China and Manchukuo to protect the air bases which formed the basis of Japan’s defensive plans, but the movement of these troops was delayed by shipping shortages. Efforts to reinforce the Mariana and Caroline island groups were assigned the highest priority, and the units selected for western New Guinea remained in China until April 1944, when the requited transport ships became available.
By a time early 1944 Allied submarines, often aided by the receipt of ‘Ultra’ intelligence, were sinking large numbers of Japanese ships: the Japanese navy routinely broadcast the location and intended route of convoys under its protection, and decryption of these signals allowed Allied naval commanders to alert submarines to make interceptions.
The Japanese navy’s poor anti-submarine concepts and tactics also contributed to Japan’s shipping losses. In the early and middle parts of the war the navy had placed a low priority on the need to protect merchant shipping, and had not instituted a convoy system until 1943, after which a dedicated Grand Escort Fleet Headquarters was created late in the year to co-ordinate convoys and implement a standard doctrine. A Convoy Escort Headquarters was added to the establishment only in April 1944 to provide a pool of senior commanders for the command of convoys, though none of the designated officers had any experience with convoy operations or anti-submarine warfare.
Continued attacks on their merchant shipping during February 1944 led the Japanese to change the composition of their convoys. During this month more than 10% of the Japanese merchant marine was sunk by submarines and air attack, the losses including several transport ships carrying army reinforcements to the Mariana and Caroline island groups. In response, the Grand Escort Fleet Headquarters increased the average size of Japanese convoys from five to between 10 and 20 ships, a change which allowed the navy to allocate more escort ships to each convoy and, it was hoped, lead to the movement of fewer convoys and thus reduce the number of targets available to submarines.
While Japanese officers attributed a drop in sinkings during March to the changed tactics, this was actually due to the diversion of many of the submarines of Vice Admiral Charles A. Lockwood’s Submarine Force of Admiral Chester W. Nimitz’s Pacific Fleet to support of the raids conducted by Rear Admiral (from later in the same month Vice Admiral) Marc A. Mitscher’s Fast Carrier Task Force.
It was within this overall context that the ‘Take 1’ convoy was assembled at Shanghai in April 1944 for the movement of Lieutenant General Yoshio Ishii’s 32nd Division to Mindanao in the Philippine islands group and the main body of Lieutenant General Shunkichi Ikeda’s 35th Division to western New Guinea. Both divisions had been formed in 1939 and were very experienced as a result of their combat in China. One of the 35th Division’s three infantry regiments had been detached from the formation earlier in April and sent to the Palau islands group, arriving there later that month without loss.
The balance of the two divisions embarked on large transport ships protected by an unusually strong escort force, and the whole undertaking was supervised by the experienced Rear Admiral Sadamichi Kajioka. Under his command Kajioka the newly established 6th Escort Convoy Command, which included Kajioka’s flagship, the minelayer Shirataka, the destroyers Asakaze, Shiratsuyu and Fujinami, the frigate Kurahashi, the ocean escort ships D-20 and D-22, the minesweeper W-2, the submarine chasers Ch-37 and Ch-38, and the gunboats Uji, Ataka and Tama Maru No. 7.
The convoy departed Shanghai for Manila on 17 April, and initially comprised 15 transport vessels as well as the ships of the 6th Escort Convoy Command. Seven of the transports were travelling only as far as Manila in the Philippine islands group, and the 32nd Division and 35th Division were each carried by four vessels.
Allied codebreakers intercepted and decrypted radio signals relating to the convoy’s departure, and subsequent intercepts allowed radio traffic analysts to follow the progress of the convoy to the south. Intelligence was used to guide the submarine Jack toward the convoy, which the submarine intercepted off the north-west coast of Luzon on the morning of 26 April. Commander Tommy Dykers, Jack’s captain, attempted to manoeuvre into a firing position but lost contact when he was forced to evade a Japanese submarine. An aeroplane sighted and attacked Jack a few minutes later, but the convoy did not change course. Dykers regained contact at about 12.00 after sighting Shirataka’s smoke and surfaced one hour before sunset to get into an attack position. Dykers was forced to dive his boat once more, however, when it came under attack from another aeroplane. Jack surfaced again after dark, and moved to attack after the moon had set. Dykers found that the Japanese escorts were alert, and was unable to penetrate the convoy. As a result, he attacked three times by firing a total of 19 torpedoes from long range into the mass of ships at the centre of the convoy: these attacks sank the 5,425-ton freighter Yoshida Maru, which was carrying an entire regiment of the 32nd Division, and 3,000 soldiers were drowned when the ship sank. The remaining Japanese ships continued to Manila, which they reached on 29 April.
During the voyage from Shanghai to Manila, the 32nd Division’s destination was changed by Imperial General Headquarters, which was concerned that the increasing difficulty of shipping units toward the front line meant that it would not be possible to complete the planned reinforcement of the ‘absolute zone of national defence’ before Allied forces reached the area. Thus it had been decided that the division would now be used to reinforce General Korechika Anami’s 2nd Area Army in western New Guinea and the eastern Netherlands East Indies, which were under immediate threat, rather than send it to Mindanao.
The ‘Take 1’ convoy resumed its voyage to New Guinea on 1 May with eight transports (one of the Manila-bound transports having replaced Yoshida Maru) under the protection of Shirataka, Asakaze, Shiratsuyu, W-22, Ch-37 and Ch-38. The convoy took a special route planned by Vice Admiral Arata Oka’s 3rd Southern Expeditionary Fleet to reduce the risk of submarine attack. US signals intelligence again detected the convoy’s departure and, on 2 May, estimated its size as nine transports and seven escorts carrying 12,784 troops of the 32nd Division and an unknown number of men of the 35th Division. Decoded messages also provided the Allies with the convoy’s route, speed, daily noon positions and destination. This highly detailed information was forwarded to the relevant commands on 2 May, and the US Navy positioned submarines to ambush the Japanese ships.
Thus it was that the ‘Take 1’ convoy suffered a major submarine attack on 6 May. On that day Gurnard intercepted the Japanese ships in the Celebes Sea near the north-eastern tip of Celebes island. The boat’s captain, Commander Herb Andrews, submerged his submarine and made a cautious approach to avoid detection by aircraft. He reached a firing position four hours later and fired six torpedoes at two transports. Only one of the torpedoes struck its mark, and a second salvo missed its intended target but hit another transport. Andrews then turned his boat and fired further torpedoes from Gurnard’s stern tubes, and these hit a third transport. One of the Japanese destroyers now counterattacked Gurnard and forced Andrews to break off his attack. The destroyer was travelling at too great a speed for its detection gear to function, however, and did not damage the submarine, despite attacks in which about 100 depth charges were dropped.
Gurnard rose to periscope depth two hours later and found that a major effort to rescue troops and equipment from the torpedoed transports was under way. That night the submarine torpedoed one of the crippled transports which was still afloat.
Gurnard’s attack sank the transports Aden Maru (5,825 tons) and Taijima Maru (6,995 tons) as well as the cargo ship Tenshinzan Maru (6,886 tons). The rescue effort was relatively successful, but even so some 1,290 troops were killed and much of their equipment was lost.
As a result of its heavy losses, the ‘Take 1’ convoy was ordered not to proceed to New Guinea, but instead to dock at Halmahera island in the eastern part of the Japanese-occupied Netherlands East Indies, where the surviving ships arrived on 9 May. Both divisions and their equipment were unloaded and the convoy sailed for Manila on 13 May, arriving on 20 May without further loss.
The attacks on the ‘Take 1’ convoy severely degraded the combat capability of the 32nd Division and 35th Division: the former’s combat elements were reduced from nine to five infantry battalions and four to one and a half artillery battalions, and the latter had lost two of its six infantry battalions as well as much of its artillery. The destruction of the ‘Take 1’ convoy also forced the Japanese leadership to acknowledge the impossibility of reinforcing or defending most of western New Guinea. Anami asked for the surviving ships to be used to move the 35th Division to New Guinea, but this request was denied by Imperial General Headquarters.
The losses inflicted on the convoy also contributed to the Imperial General Headquarters’ decision to move the perimeter of the ‘absolute zone of national defence’ back 600 miles (965 km) to the line linking Sorong in western New Guinea to Halmahera.
Japanese naval officers met in Manila during June to analyse the ‘Take 1’ convoy. The officers believed that Japan’s communication codes were secure and discussed alternative explanations for the convoy’s detection. These explanations included the Allied detection of the increase in radio signals at the time the convoy sailed, a Japanese officer in Manila accidentally divulging information, and Allied spies working on the Manila waterfront, and the meeting concluded that it was the last which was responsible for the convoy’s detection. The Japanese military codes were therefore not changed.
Some of the surviving elements of the 32nd Division and 35th Division later saw action against the US forces. The 35th Division was moved forward from Halmahera to Sorong in small ships during May, and its regiment detached to the Palau islands group in April was also successfully transferred to New Guinea. Elements of the 35th Division were later involved in the ‘Horlicks’ and ‘Globetrotter’ battles for Biak and Sansapor respectively, but most of the division was stationed on the Vogelkop peninsula, where it was isolated from September 1944. The 32nd Division was retained as the garrison of Halmahera, and much of this formation later saw action on the neighbouring island of Morotai, where it suffered heavy losses while trying to counterattack an Allied force which had established a base there in ‘Interlude’ during September and October 1944.