'ME3' was a British naval diversion by Admiral Sir Andrew Cunningham’s Mediterranean Fleet in support of the 'Substance' passage of the GM.1 convoy from Gibraltar to Malta (22/25 July 1941).

In order to distract German and Italian attention from the western and central parts of the Mediterranean, through which the GM.1 convoy was passaging, and despite the losses which his Mediterranean Fleet had recently suffered in the operations to extract British forces from Greece and Crete, Cunningham arranged 'ME3' on the basis of foray in the eastern basic of the Mediterranean by a substantial force from Alexandria and Haifa. Departing at 21.00 on 22 July, the Alexandria force comprised the battleships Queen Elizabeth and Valiant, the light cruisers Neptune and Australian Hobart, the light anti-aircraft cruisers Naiad and Phoebe, the cruiser minelayers Abdiel and Latona, and the destroyers Griffin, Hasty, Havock, Jackal, Nizam and Nubian, while that departing Haifa comprised the light cruisers Ajax and New Zealand Leander and the destroyers Jaguar, Jervis, Kandahar and Kingston.

The two forces met at 06.00 on the following day and steered to the west in the direction of the central Mediterranean, making no effort to avoid detection by Axis forces, but turned back to the east after the fall of night. Two submarines surfaced and transmitted spurious radio signals in the position which the surfaces might be expected to have reached by the break of day on 24 July.

The surface vessels had returned to base by 25 July.