Convoy GP55

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LST-469 is being repaired after the attack
A World War II-era submarine in a body of water with a land mass in the background
Japanese submarine I-168 , I-174 belonged to the same class

The convoy GP55 was a convoy of Allied ships that ran from Sydney to Brisbane during World War II in June 1943 .

It consisted of a total of ten cargo ships, three landing ships and an escort of five corvettes . The Japanese submarine I-174 attacked the convoy on June 16 and sank the US Army transport ship Portmar while the landing ship LST-469 was badly damaged. Two of the corvettes responded to the attack from I-174 , but could only damage it slightly.

The Australian military conducted an intensive search for I-174 in the days that followed the attack, mistakenly believing that the submarine was badly damaged in the counterattack.

This search was unsuccessful and blatantly revealed the weaknesses in communication between the Royal Australian Navy (RAN) and the Royal Australian Air Force (RAAF).

Due to the steadily deteriorating strategic position of Japan, I-174 was the last submarine of the Imperial Japanese Navy that operated off the Australian east coast until the end of the war in 1945.

background

Japanese submarines conducted intermittent operations in the waters around Australia in 1942 and 1943. A flotilla of micro-submarines attacked Port Jackson on the night of June 1, 1942. In the days that followed, merchant ships sailing the west coast of Australia were attacked. These attacks continued until November 1942, when the submarine forces were relocated to other waters. I-174 , a Kaidai-class submarine, patrolled Australian waters in July and August 1942, but had not participated in any attack until then. In response to the ongoing Japanese attacks, the Australian Navy ordered that from June 8, 1942, every ship with a displacement of more than 1200 ts and a maximum speed of less than 12 knots should operate in armed convoys. This escort strategy was successful and minimized its own losses, so that by the end of 1942 no other ship was lost in the vicinity of Australia due to enemy action.

Japanese submarines resumed operations in Australian waters in January 1943. I-21 sank five ships on patrol in January and February. Two other submarines carried out operations near Sydney and Brisbane in March. Five submarines of the Japanese 3rd submarine squadron then attacked the Allied fleet along the entire Australian coast with the intention of disrupting the Allied supply routes to New Guinea . At that time, the activities of Japanese submarines in the battle against Australia were at their peak. Eight ships were sunk near the west coast of Australia during the month. In contrast to 1942, this time some attacks on ships in the convoy group ended successfully.

The numerous attacks in 1943 put a heavy strain on the Allied forces charged with defending the convoy on the Australian west coast. The Australian leadership was forced to reduce the number of convoys in order to adhere to a minimum number of four ships per convoy prescribed by the naval leadership. In addition, the RAAF increased the number of aircraft dedicated to escorting convoys and individual ships. Other ships and aircraft specially equipped for use against submarines were deployed from May onwards, but these forces were not sufficient to effectively counter the threat posed by the Japanese armed forces.

The sinking of the hospital ship Centaur on May 14, 1943, which killed many people, led the Advisory War Council to demand practical solutions from the RAN and the RAAF, above all to protect the lives of the ship's crews. At this point, the RAN found that the Bathurst- class corvettes , which formed a large part of the escort forces, were reaching too low a speed. However, the Navy was of the opinion that the losses in the convoys were no greater than in other theaters of war. Despite this finding, the effectiveness of the Australian anti-submarine forces was limited due to a lack of training facilities and a lack of coordination between the Australian and United States Navy and the Air Force. In addition, the Australians did not keep pace with the introduction of tried and tested new anti -submarine tactics by the Americans and British.

Attack on the convoy

On May 16, 1943, I-174 left the Japanese naval base on Truk Island . The commander of the boat was Chu-i Nobukiyo Nanbu. On May 27, the boat reached the waters not far from Sandy Cape, Queensland . It was the only Japanese submarine that carried out operations on the coast of Australia at the time, all other submarines fought allied ships in the Solomon Islands area . On June 1, I-174 made contact with the enemy for the first time, but the torpedoes missed the US-flagged Point San Pedro . Three days later it was involved in an artillery duel with the transporter Edward Chambers . On June 5, the escort of convoy PG 53, I-174 succeeded in preventing an attack on the convoy. On June 7th, the boat fired four torpedoes at the American Liberty freighter John Bartram , but they missed the target. Another convoy was sighted on June 13, but was too far away for an attack to be worthwhile. At that time, I-174 was attacked several times by Allied ships and aircraft, but remained undamaged.

In mid-June 1943 the convoy GP55 was put together, one of at least 69 sea convoys that traveled the route Sydney – Brisbane in 1943. It consisted of ten transport ships and three landing ships ( LST ). He was accompanied by Bathurst- class corvettes : Warrnambool (convoy lead ship), Bundaberg , Cootamundra , Deloraine and Kalgoorlie . After the convoy left Sydney on the morning of June 15 at 8:45 a.m., the ships formed into five columns with five ships in the central columns and two in the outer columns. Four of the escorts ran in front of the formation while the Deloraine ran behind the convoy. The air security of the convoy consisted of RAAF aircraft of the type Avro Anson and Bristol Beaufort . The American transport ship Portmar , which was badly damaged in the Japanese air raid on Darwin on February 19, 1942, had great difficulty holding the formation, so that it slowly fell back from the convoy.

I-174 sighted GP55 at 4:37 pm on June 16 approximately 35 miles west of the islands of Smoky Cape . The submarine managed to get into the firing position through the shielding escort without any problems. At that moment the Portmar tried to catch up to the original position in the convoy. She was now not far from DropShip LST-469 . As a result, the ships were in the optimal attack position for Chu-i Nanbu at the moment of overtaking.

At 5:20 p.m., two torpedoes left the I-174 tubes . A torpedo hit the American DropShip in the central nave and severely damaged it. The explosion killed 26 sailors and wounded a further 17. The Portmar sighted the second torpedo and tried an evasive maneuver, which however failed. The Portmar was hit in the forecastle . The ship's cargo, mainly fuel and ammunition, caught fire quickly, so that the ship sank within ten minutes. One crew member and one passenger died, 71 survived and were subsequently rescued by the corvette Deloraine . Although LST-469 was unable to maneuver, it remained afloat and was towed by the corvette. This attack by I-174 on the GP55 convoy was probably the most effective attack by a Japanese ship anywhere near Australia.

While the Deloraine was on a direct route to the torpedoed ships, the remaining four corvettes made an attempt to locate the enemy. I-174 went undetected while approaching the convoy. After the attack, the escort ships caused a change of course, with which they began to track the enemy with the help of sonar. This was the RAN's most recently updated tactic, and it had been effective in combat in the Atlantic. 23 minutes after the attack, the Warrnambool discovered the submarine and carried out, together with the Kalgoorlie, four attacks with depth charges over a period of two hours on I-174 . After that, sonar contact with the submarine was lost.

A 71st Squadron Avro Anson escorted the convoy just as the attack occurred. However, due to a lack of fuel, she had to fly back to her base shortly after the attack. While the escort commanders were convinced they had sunk the enemy, I-174 was only slightly damaged and retreated east. This failure for the Australians resulted from insufficient experience and the insufficient number of ships that would have enabled an adequate approach to a systematic search.

After the end of the search, the Warrnambool rejoined the convoy, while the Kalgoorlie helped the Deloraine protect the damaged DropShip. Heavier seas meant that the towline between the Deloraine and LST-469 tore. Then the Deloraine set course for the port of Coffs Harbor with the survivors of the Portmar and the injured crew members of the landing ship. On June 16, the tug Reserve left Brisbane to tow the damaged DropShip to Sydney. They arrived there together on June 20th.

LST-469 carried soldiers and supplies for Operation Chronicle , an amphibious landing operation that took place on June 30th on the islands of Woodlark and Kiriwina . The operation was made more difficult by the damage caused by the attack by I-174 on the DropShip.

Consequences of the attack

After the attack, Admiral Sir Guy Royle , Chief of Naval Staff, stated that the submarine responsible for the attack had been damaged in the counterattack and ordered “special steps” to be taken to To locate the boat.

The RAAF undertook a search operation on the night of June 16-17 on an area of ​​80 square miles west of Coffs Harbor, while the Deloraine , Kalgoorlie and the incoming destroyer Vendetta patrolled the area. On June 17, Anson-type aircraft were assigned to patrol the submarine's most likely escape route in the hopes that this would force the boat to maintain the combat rhythm of diving during the day and ventilation at night. During the night, the Ansons were replaced by the Beauforts, which had radar equipment.

The Deloraine

On the morning of June 18, two Beauforts from the RAAF's 32nd Squadron bombed and machine gun fire attacked an object they believed was a surfaced submarine. The Deloraine was not six nautical miles away from the scene at the time, but did not respond to the aircraft's attempts to spark it. The planes reported that they had made contact with the enemy. The attempt to localize and combat again was continued the following day. Twelve Anson were on constant search over the sea, while six dive bombers type Vultee A-31 Vengeance waited on the alert for deployment. No targets were found, however, so it was assumed that the enemy, attacked by a 32nd Squadron aircraft the day before, was damaged but escaped after the attack. However, the target attacked on June 18 could not have been a submarine as I-174 was at least 60 miles west of the location where the attack occurred and no attack was in I- 174 was noted. The submarine was ordered to evacuate from Australian waters on June 20 and arrived back in Truk on July 1 without any contact with other Allied units after the attack on the convoy.

The attack on convoy GP55 was the last attack by a Japanese submarine near the Western Australian coast. Two other submarines were assigned to patrol the Australian west coast in July 1943, but changed their course shortly before arriving in the target area and started at the Solomon Islands. The submarines were later concentrated for defense against the Allied sea offensives and for the transport of supplies to enclosed garrisons. Since the danger for the ship's crews diminished after the time, the RAN stopped the formation of escorted convoys in the waters around the west coast of Australia from the city of Newcastle ( New South Wales ) on December 7, 1943 , the same happened on February 10, 1944 for the Sydney – Brisbane route.

literature

Footnotes

  1. ^ David Stevens: Japanese submarine operations against Australia 1942-1944 . In: Australia-Japan Research Project . Australian War Memorial. Archived from the original on February 19, 2017. Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Retrieved July 19, 2009. @1@ 2Template: Webachiv / IABot / ajrp.awm.gov.au
  2. ↑ Stevens (2005), pp. 194-95, 201-03.
  3. ↑ Stevens (2005), p. 355.
  4. ↑ Stevens (2005), p. 195.
  5. ↑ Stevens (2005), p. 205.
  6. ↑ Stevens (2005), pp. 218-20, 223-24.
  7. ↑ Stevens (2005), pp. 230-31.
  8. ↑ Stevens (2005), pp. 253-62.
  9. ↑ Stevens (2005), pp. 236-37.
  10. ↑ Stevens (2005), p. 239.
  11. ↑ Stevens (2005), pp. 239-242.