Ill-fortune struck again during their return when the vessel in which they were travelling, the Royal Mail Steam Packet Company, Boyne, ran aground on Friday 13 August on the rocks off the Isle of Molene, near Brest, France.

In 1930 he was assigned to the battleship Marlborough, part of the Third Battle Squadron; and the following year to the battlecruiser Renown in September 1931 on which he served with fellow midshipman, and future vice admiral, Peter Gretton.

Admiralty orders dictated any Nationalist or Spanish Republican Navy vessel that attempted to attack British shipping was to be sunk on sight.

[15] Wanklyn returned to Gosport in July 1939 and became the first lieutenant and second-in-command of HMS Otway, part of the 5th Submarine Flotilla, in August 1939.

It left the navy defending British waters against a hostile coastline which ran from northern Norway to the French Atlantic Ocean coast.

For the next thirty minutes eight depth charges were directed at the submarine, the nearest detonating 250 yards (230 m) away, before the enemy gave up and retired eastward.

[25] Ten days later, on 22 February, restrictions on British submarines were lifted and shipping in the entire Mediterranean Sea was considered fair game and to be sunk on sight.

He fired a star shell over the convoy to mark its position and the enemy fleet quickly reversed direction to port.

[29] In early April, British naval intelligence received a report that Albert Kesselring, the Luftwaffe (German air force) commander-in-chief for the Mediterranean, was setting up his headquarters at the Miramar Hotel in Taormina in Sicily.

Simpson selected Wanklyn and Upholder for an operation to land commandos onto enemy-held coastland for an assassination attempt against Kesselring.

[30] Simpson received a report from naval intelligence that two enemy cruisers and destroyers were leaving port in Sicily to rendezvous with a convoy south of Kerkennah Islands.

On 25 April Wanklyn spotted a merchant ship and its armed trawler escort but managed to close to 700 yards (640 m) undetected before firing two torpedoes.

Unable to risk torpedoes in such shallow water, he moved alongside the transport, which had been heavily damaged in an attack and appeared to be deserted, with no live personnel on board.

Wanklyn's letters to his wife usually carried the address of San Anton Palace, where he became the frequent guest of the governor General Sir William Dobbie.

Three torpedoes were fired and Capitaine Damiani, a Vichy French vessel travelling under Italian charter, sank by the stern roughly five nautical miles (9.3 km; 5.8 mi) south-west of Punta di Pellaro.

Alberta carried out evasive action and the escorting vessels dropped 26 depth charges and hunted Upholder all afternoon.

He heard two explosions and the ship, carrying the flag of Rear Admiral Francesco Canzoneri, sank with 2,279 soldiers and crew on board roughly 50 km (27 nm) east of Portopalo di Capo Passero in Sicily.

While off combat duty, Wanklyn lectured and tutored new officers if he was asked, but preferred not to force junior commanders to listen to his experiences.

Simpson did not want to expose Upholder to undue risk in his absence, and the submarine was allotted the Messina to Tripoli route, rather than allowing it to conduct operations close to the enemy shore.

Two explosions were heard and distress signals identified her as Laura C. The destroyer dropped 19 depth charges, which shattered light bulbs and came close to damaging the submarine.

The destroyer dropped 17 depth charges over two hours and attempted a hydrophone hunt, but Wanklyn dived to 150 feet (46 m) and retired to the north-west.

It was identified as the Giuseppe Garibaldi, travelling at high speed—the asdic gave a reading of 230 revs indicating 28 knots (52 km/h; 32 mph).

On 15 August 1941 Wanklyn and Upholder sailed to the Marittimo area with the hope of landing saboteurs—or train wrecking parties—along the coast to plant explosives along coastal railways.

The London Gazette published the exploits of Wanklyn and he became a well-known figure in Britain and the men were given two weeks leave on Malta.

This convoy was later intercepted, and the tanker sunk, by Force K. On 29 November Upholder sailed into the midst of an Italian naval squadron on a night exercise.

With the closest vessel only 3,000 yards (2.7 km) away Wanklyn continued to calculate the bearing and speed of the enemy, until eventually he ordered the boat to dive.

Many newspapers used his picture and interview with the Times of Malta, made earlier in the year, to draw on his account of the sea war.

The men standing on the conning tower survived: Lieutenant Como, Petty Officer and Telegraphist Valentino Chico and Torpedoman Ernst Fiore.

The most likely explanation is that she fell victim to depth charges dropped by the Italian torpedo boat Pegaso north east of Tripoli on 14 April 1942, although no debris was seen on the surface.

More recent research carried out by Italian naval specialist Francesco Mattesini points to a German aerial patrol supporting the same convoy, composed of two Dornier Do 17s and two Messerschmitt Bf 110s, which attacked an underwater contact with bombs two hours before the Pegaso incident.