HMS Triad (N53) was a T-class

British T class submarine

The Royal Navy's T class of diesel-electric submarines was designed in the 1930s to replace the O, P and R classes. Fifty-three members of the class were built just before and during the Second World War, where they played a major role in the Royal Navy's submarine operations...

 submarine

Submarine

A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

 of the Royal Navy

Royal Navy

The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

. She was laid down by Vickers Armstrong

Vickers Armstrong

Vickers-Armstrongs Limited was a British engineering conglomerate formed by the merger of the assets of Vickers Limited and Sir W G Armstrong Whitworth & Company in 1927...

, Barrow

Barrow-in-Furness

Barrow-in-Furness is an industrial town and seaport which forms about half the territory of the wider Borough of Barrow-in-Furness in the county of Cumbria, England. It lies north of Liverpool, northwest of Manchester and southwest from the county town of Carlisle...

 and launched in May 1939. So far she has been the only ship of the Royal Navy to bear the name Triad.

Career

Triad had a relatively short career, serving in the North Sea

North Sea

In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...

 and the Mediterranean. In April 1940 she sank the German troop transport Ionia and attacked, but failed to sink the German depot ship Tsingtau.

Mediterranean and loss

Shortly after, she was assigned to the Mediterranean. On 9 October 1940 she sailed from Malta

Malta

Malta , officially known as the Republic of Malta , is a Southern European country consisting of an archipelago situated in the centre of the Mediterranean, south of Sicily, east of Tunisia and north of Libya, with Gibraltar to the west and Alexandria to the east.Malta covers just over in...

 to operate in the Gulf of Taranto, with orders to reach Alexandria

Alexandria

Alexandria is the second-largest city of Egypt, with a population of 4.1 million, extending about along the coast of the Mediterranean Sea in the north central part of the country; it is also the largest city lying directly on the Mediterranean coast. It is Egypt's largest seaport, serving...

 on completion of her patrol. She failed to make port and by 20 October the submarine was declared overdue. She was believed to have been lost in a minefield or sunk by Italian anti-submarine aircraft. New evidence suggests that Triad was engaged and sunk on the night of 14/15 October by the Italian submarine Enrico Toti.

It was assumed that the Enrico Toti had engaged and sunk HMS Rainbow, which was thought to be operating in the same area.

Last action

At 0100 hours on 15 October, the Enrico Toti sighted a large submarine 1,000 metres to port: both boats manoeuvred into attack position but the British opened fire first, scoring two hits, one on the Conning Tower, the other on the bow. She also fired a torpedo which Enrico Toti avoided by turning sharply, then closed on the enemy submarine at top speed, firing as she approached. Soon, machine gun fire compelled the British gunners to abandon the exposed deck. As the British submarine started to dive, Toti fired a torpedo and hit the British submarine with two shells. The boat rose vertically then disappeared without survivors. The entire action had lasted less than 30 minutes

Rainbow had been ordered to leave the area on 13 October, she would have been gone 26-30 hours before the action described above began. Even at the modest speed of 6 knots (11.8 km/h), Rainbow would have been 200 nautical miles (370.4 km) away from the spot at the time of the action. The only boat in Toti's vicinity was Triad.