'Mitre' was a British naval undertaking to sink the Japanese heavy cruiser Haguro as a consequence of 'Dukedom' (10/16 May 1945).

Haguro had been operating as a supply ship for Japanese garrisons in the Netherlands East Indies and the occupied islands in the Bay of Bengal since 1 May 1945, and on 9 May departed Singapore, escorted by the destroyer Kamikaze, to deliver urgently needed supplies to the Japanese garrison of Port Blair in the Andaman islands group, and to evacuate troops back to Singapore.

The British were alerted to this movement by the decryption of a Japanese naval signal, and then a sighting of the two ships as they headed to the north-west along the Malacca Strait, by the submarines Statesman and Subtle.

While his Force 61 (battleships Queen Elizabeth and French Richelieu of the 3^rd Battle Squadron, the heavy cruiser Cumberland, the Free Dutch light cruiser Tromp, the light anti-aircraft cruiser Royalist, the escort carriers Emperor, Hunter and Khedive, and seven destroyers) was returning to Trincomalee in Ceylon to rejoin the rest of Vice Admiral Sir Arthur Power’s East Indies Fleet after providing support for the 'Dracula' operation to take Rangoon, on 11 May Vice Admiral H. T. C. Walker had decided to take advantage of the fact that the escort carriers were close to Car Nicobar to launch a Hellcat fighter-bomber attack which destroyed a few Japanese aircraft on the airfield, but this attack probably alerted the Japanese to the presence of a powerful naval force possibly awaiting Haguro and her consorts.

The Japanese were unwilling to risk battle under what were patently very disadvantageous terms and, on receipt of a specific air reconnaissance warning, had turned back toward Singapore.

The British expected the Japanese to make a second attempt to complete their mission, however, and Walker took his force well to the south to avoid any realistic chance of being discovered once again by Japan reconnaissance. On the night of 14/15 May Walker detached the 21^st Carrier Squadron (escort carriers Emperor, Hunter, Khedive and Shah carrying 42 Grumman Hellcat fighter-bombers, 21 Supermarine Seafire fighters, nine Grumman Avenger attack aircraft and two Supermarine Walrus spotter amphibian flying boats), the heavy cruiser Cumberland and the destroyers Saumarez, Venus, Verulam, Vigilant and Virago (Captain M. L. Power’s 26^th Destroyer Flotilla) to search the waters to the north of Sumatra for the Japanese warships and also for any merchant shipping.

As a British submarine had sighted Haguro heading south-east toward Singapore after receiving the information that two British destroyer squadrons and other warships had been sighted heading toward them, the escort carriers were now concentrating their efforts on the location and destruction of Japanese merchant shipping in the Malacca Strait. Shah's catapult became unserviceable in 15 May, and her Avenger aircraft were therefore transferred to Emperor, which was optimised for the assault support role and thus lacked the facilities for arming and briefing a torpedo-bombing operation. One of the Avenger aircraft, searching for merchant shipping, then found the cruiser, the destroyer and two submarine chasers off Sabang, which had departed Singapore once more on 14 May, just before 12.00 on 15 May.

As a result of the congestion on Emperor's deck, there were not enough Avenger aircraft to shadow the Japanese warships, and only three of the aircraft could be launched 90 minutes later to attack the cruiser. The aircraft regained contact with the Japanese surface force after two hours and the dive-bombing resulted in just one very near-miss forward: one Avenger of No. 851 Squadron was lost and its crew taken prisoner by the Japanese. Little more could be expected with such a small force with scant recent training in the shipping strike role and operating under such adverse conditions.

The Japanese ships reversed course and were once again heading for Singapore, but Walker had foreseen this and detached Power with his five destroyers. In poor conditions with heavy rain and lightning, at 23.00 Venus gained radar contact at a range of 39 miles (63 km). The destroyers now deployed into a crescent cordon attack formation and allowed the Japanese ships to steam into this trap.

At 01.05 Venus, on a course parallel to that of Haguro as the cruiser raced past the most north-westerly ship in Power’s trap, found herself in a perfect attacking position. But the British destroyer’s torpedo control officer entered the wrong angle settings on her eight tubes, and thereby lost the opportunity. Venus heeled hard over to port to clear the target area but still maintain the encirclement. Thinking that Venus had in fact launched torpedoes, Haguro turned away from the supposed torpedo launch position to open the range and also present the smallest position target by combing the torpedo tracks. However, in so doing, the cruiser turned to the south and in the process moved deeper into the British destroyers' trap.

Saumarez and Verulam were now nicely positioned to make their attacks. Haguro appeared fine off Saumarez '​s port bow at a range of 6,000 yards (5485 m), each ship closing at 30 kt. At the same time Kamikaze appeared off the starboard bow, crossing from starboard to port, only 3,000 yards (2745 m) distant and on a collision course. Saumarez's second salvo from her two radar-controlled forward 4.7-in (119.4-mm) guns struck Kamikaze and 40-mm Bofors shells from the British ship’s after twin mounting ripped the whole length of the Japanese destroyer as Saumarez heeled violently to starboard. By now Haguro had fired her first broadside from 10 8-in (203-mm) and four 5-in (127-mm) guns, and the impacting shells raised great waterspouts alongside Saumaraz, swamping the flotilla leader’s upper decks. Haguro could be seen clearly, some 5,300 yards (4845 m) distant, in the light of each side’s star shells, her guns depressed to their lowest angle.

At 01.11, on the verge of firing torpedoes, Saumarez was hit: the top of her funnel disappeared over the side and a 5-in (127-mm) shell penetrated one of her boiler rooms, severing a steam main and lodging inside the boiler. Two men were killed and three others were scalded: like the 8-in (203-mm) hits, though, the shell failed to explode at such close range and was later thrown overboard.

At 01.15, Haguro was hit by three torpedoes from Saumarez and Verulam. As the former limped away to the north out of the immediate battle area, a violent explosion created confusion: Power thought it was Kamikaze blowing up, and Virago and Vigilant thought that it marked the end of Saumarez, but it was probably two torpedoes colliding. Venus hit Haguro with one torpedo at 01.25, and Virago brought Haguro to a halt with two more torpedo hits a couple of minutes later. Haguro began to list 30° to port and settle by the stern, and succumbed at 02.06 in a position some 55 miles (90 km) to the south-west of Penang as the last major Japanese warship to be sunk in World War II, after receiving another torpedo from Vigilant, two more from Venus, and nearly one hour of gunfire from the ships of the 26^th Destroyer Flotilla.

Kamikaze was also damaged, but escaped before returning on the following day to rescue survivors. About 320 men survived, but among the total of more than 900 men who died were the Japanese commanders, Vice Admiral Shintaro Hashimoto and Rear Admiral Kaju Sugiura.