This was a British naval programme of carrierborne air attacks and warship gunfire bombardments, under the command of Rear Admiral W. R. Patterson, commander on the 5th Cruiser Squadron in Vice Admiral Sir Arthur Power’s East Indies Fleet, on installations on the Japanese-occupied Nicobar islands group to the north of Sumatra (5/10 May 1945).
The objectives of the operations were firstly, to undertake a naval bombardment and air attacks on Japanese positions in the Nicobar islands group and especially on Cap Nicobar and Nancowry islands; secondly, to provide cover for minesweeping operations by the vessels of Commander D. L. Johnson’s 6th Minesweeping Flotilla as they cleared mines from the waters between the Nicobar islands group and Phuket island off the south-west coast of Thailand in advance of a possible invasion; and thirdly, to make carrierborne air raids on the Japanese airfields at Kota Raja and Lho Nga in the northern part of Japanese-occupied Sumatra.
The ships of Patterson’s Task Force 61 for this undertaking were the escort carriers Ameer and Emperor, light cruiser Nigeria, and destroyers Eskimo, Roebuck and Vigilant, and those of Johnson’s Force 62 were the minesweepers Elnnox, Gozo, Lightfoot, Melita, Pelorus, Persian, Postillion, and the danlayers Immersay and Lingay to provide navigational support.
The ships of Forces 61 and 62 departed Trincomalee in Ceylon during the morning of 2 July and proceeded directly to Car Nicobar. The destroyers and minesweepers refuelled from the carriers on passage and as necessary during the operation.
The minesweepers operated off Car Nicobar daily from 5 to 10 July, and the 167 moored mines which were swept were all in the area to the east of the island.
In order to cover the activities of the minesweepers, Nigeria and the destroyers undertook gunfire bombardments of the Japanese coastal gun positions and targets of opportunity on the island, while the Grumman Hellcat fighter-bombers of Nos 800 and 896 Squadrons carried out a series of attacks, during which radar stations were put out of action and all craft seen in the area rendered unseaworthy.
The only Japanese reaction was accurate anti-aircraft fire. Four of the British aircraft were shot down, but all the pilots were rescued inshore, one by a Supermarine Walrus amphibian flying boat aircraft flown off Emperor and the others by destroyers, who movements close inshore drew heavy but ineffective machine gun fire.
Precautionary measures against a possible landing, including the erection of stakes on airfield runways, were taken by the Japanese.
On 7 July, Nancowry was taken under naval gunfire bombardment and was also attacked by aircraft operating in heavy rain squalls. Fires and explosions were observed in the area of Naval Point and two coasters were left on fire. Two of the British aircraft were shot down by anti-aircraft fire, the pilot of one of the machines being rescued.
At first light on 11July, a force of 24 Hellcat warplanes attacked Kotaraja and Lhonga airfields in the north-western part of Sumatra. No aircraft were seen on either of these airfields, or at Sabang, but the runways and buildings were nonetheless bombed and strafed. After being hit by anti-aircraft fire, one Hellcat force landed in the sea, the pilot being picked up by a destroyer. One Japanese aeroplane which approached the British warships was shot down by fighters.
It is worth noting that accounts of the British air losses vary, one source admitting six aircraft losses, three of them to Japanese action, together with two pilots killed, and another conceding seven aircraft lost but no pilots killed.