'Meridian I' was a British carrierborne air attack on the oil refineries at Palembang on Sumatra island in the Japanese-occupied Netherlands East Indies (24 January 1945).

The two oil refineries at Palembang were the largest in South-East Asia, between them capable of meeting three-quarters of Japan’s total requirement for aviation fuel, and were thus a target of considerable strategic importance. In November 1944 the British Pacific Fleet (intended for service alongside the larger forces of the US Navy in the Pacific) had received a dynamic commander in Admiral Sir Bruce Fraser as it was forming at Trincomalee in Ceylon, with Rear Admiral Sir Philip Vian commanding its fast carrier force, comprising Illustrious, Indefatigable, Indomitable and Victorious.

The British Pacific Fleet was scheduled to move from Ceylon to Australia during January 1945 before joining in Pacific operations, and this gave the carriers of Vian’s Task Force 63 an ideal opportunity to raid the Palembang refineries and so confirm the operational capability of their new Grumman Avenger attack aircraft after the limited successes of the two earlier raids, those against the refinery at Belawan Deli in north-eastern Sumatra on 20 December 1944 ('Outflank') and 1 January 1945 ('Lentil').

Vian’s strength was centred on Task Force 63, in which the four fleet carriers were supplemented by the battleship King George V, the light anti-aircraft cruisers Argonaut, Black Prince and Euryalus, the 25^th Destroyer Flotilla (Grenville, Undine, Ursa and Undaunted) and the 27^th Destroyer Flotilla (Kempenfelt, Wakeful, Whirlwind, Wager, Whelp and from 19 January 1945 Wessex), and its supporting Task Force 69 of the East Indies Fleet with the light cruiser Ceylon, the destroyer Urchin and the fleet oilers Echodale, Empire Salvage and Wave King, which departed Ceylon on 13 January, and Arndale, which departed Fremantle in Western Australia two days later. The associated reconnaissance and air-sea rescue duties were allocated to the submarines Sturdy, Tantivy and Tantalus.

'Meridian I' was launched on 24 January and 'Meridian II' on 29 January. TF63 departed Trincomalee in Ceylon on 13 January bound for Sumatra, and on 20 January rendezvoused with TF69 to refuel, a task accomplished only with great difficulty because of gusting winds and a troublesome swell. The oilers complained that much of their equipment had been damaged. 'Meridian I', the attack on the oil refinery at Pladjoe, to the north of Palembang, was delayed by poor weather. On 21/22 and 22/23 January the weather off Sumatra prevented the launch of carrierborne aircraft, the fleet waiting off Enggano island, and the attack was finally launched at 06.00 on 24 January: 43 Grumman Avenger bombers, 12 Fairey Firefly fighter-bombers armed with rockets, and 50 Grumman Hellcat, Vought Corsair and Supermarine Seafire fighters were launched and swept in to attack the target area. The Japanese defences were taken by surprise: only about 20 Japanese army air force fighters were able to take-off, and 14 of these were shot down; another 31 Japanese fighters were destroyed on the ground on the complex of three airfields protecting the area. The British lost seven aircraft in combat, and 25 as a result of crash landings.

The attack reduced Pladjoe’s output of aviation fuel by half. After replenishing on 26/27 January in an unsatisfactory undertaking marred by poor weather and inexperience causing hoses to part and oilers to be damaged as ships failed to keep station properly, TF63 returned on 28/29 January and early on 29 January flew off 48 Avenger, 10 Firefly, 24 Corsair and 16 Hellcat warplanes to make a raid on the oil refineries at Soengi-Gerong near Palembang. Some 30 Japanese aircraft were shot down, in combat and another 38 destroyed on the ground; 16 British aircraft did not return, although some of their crews were rescued.

An attempted Japanese attack on TF63 with 12 bombers was intercepted by the British combat air patrol, and all the bombers were shot down by fighters and anti-aircraft fire.

After again refuelling from the oilers on 30 January, the ships of TF63 proceeded to Fremantle in Western Australia, which they reached on 4 February.