HMS Avon (K97): From Convoy Escort in the Atlantic to Task Force 57 Off Okinawa

A Frigate Built to Stretch Resources Further

HMS Avon was built by Smith's Dock Company of South Bank-on-Tees as a Group II River-class frigate, one of 151 River-class ships launched between 1941 and 1944 and named, in keeping with the class's tradition, after a British river.

The design was intended to combine much of the endurance and anti-submarine capability of the larger Black Swan-class sloops with a considerably more economical build, allowing Britain to produce capable convoy escorts in the kind of numbers the Battle of the Atlantic demanded.

Smith's Dock deserves naming properly, because that one firm on the Tees designed the two escort types that carried the Battle of the Atlantic. The Flower class corvette came out of their drawing office, adapted from a whale catcher, and when the Flower proved too small, too slow and too wet for the mid-ocean, the same designer went back and produced the River. A hundred and fifty-one Rivers were built, in Britain, Canada, Australia and the United States. It is difficult to think of another commercial shipbuilder anywhere that had that much influence on the outcome of a naval campaign.

Commissioned on 18 September 1943 under Lieutenant Commander Patrick King, RNR, she worked up with anti-submarine exercises off Tobermory before joining convoys out of Londonderry that winter.

She carried Hedgehog anti-submarine mortars and depth charges as her primary weapons against the U-boat threat.

A Rescue in the Indian Ocean

Avon spent much of the war on exactly the kind of unglamorous, essential North Atlantic convoy escort duty her class was built for, but her most notable single action came further afield: in 1944 she rescued survivors of the torpedoed Norwegian freighter Tarifa in the Indian Ocean, a ship that had been carrying Australian troops home from North Africa, a rescue that likely saved a considerable number of Allied soldiers' lives far from the war's more famous battles.

Tarifa had been sunk on 7 March 1944 by the German submarine U-510 some 250 nautical miles east of Socotra Island; Avon reached the scene on 13 March and pulled 123 survivors from the water.

The Indian Ocean rescue is worth a little context, because U-boats that far east were a genuine oddity. From 1943 Germany operated a small number of boats out of Penang in Japanese-occupied Malaya, supplying them by submarine tanker and using them against the sparse, poorly escorted traffic between the Gulf, India, Australia and Africa. U-510 was one of them, and one of very few that eventually got home. Two hundred and fifty miles east of Socotra is about as far from a rescue service as the sea gets, and Avon reached the survivors six days after the sinking, which tells you how long 123 people had been in boats and on rafts in the tropics before anybody arrived.

The following year she took part in the Battle of Okinawa as part of Task Force 57, the British Pacific Fleet's carrier force, supporting one of the largest and bloodiest amphibious operations of the entire Pacific War, a considerable distance both geographically and in character from her earlier Atlantic convoy work.

Her role there was largely to screen the fleet's logistic support group, escorting RFA tankers through their replenishment runs, including on 3 and 4 May 1945, so that the carriers themselves could stay on station off Okinawa rather than withdraw to refuel.

Screening the logistic support group sounds like the dullest job in the Pacific and was, in fact, the thing the entire British effort turned on. The Royal Navy had spent the whole war operating within reach of a friendly harbour: Scapa, Gibraltar, Alexandria, Trincomalee. Sending a fleet to fight off Okinawa meant supporting it four thousand miles from Sydney with no base in between, and Britain had to build a Fleet Train from scratch out of requisitioned merchantmen and whatever else could be found. It ended up as ten repair and maintenance ships, twenty-two tankers, twenty-four store carriers, four hospital ships, five tugs, eleven cargo vessels and two floating docks, assembled by a country whose merchant fleet had already been savaged.

The Americans were not convinced it would work. Admiral Ernest King's objection to a British fleet in the Pacific was not about flags or pride but about supply: he did not believe the Royal Navy could keep itself fed, fuelled and repaired that far forward, and he was not willing to have American logistics carry a British force. So Task Force 57 had to prove it. The pattern was two days of strikes followed by two days of replenishment, and on 3 May 1945 the fleet made its first rendezvous with the Logistic Support Group at a position codenamed Mosquito. It did not all go smoothly, the cruiser Uganda managed to wrap a fuel hose round a propeller, but it worked, and it went on working until the war ended.

Avon's part in that was to be one of the ships standing guard while it happened. Replenishment at sea leaves both vessels tied together by hoses, steaming a steady course and speed, unable to manoeuvre and unable to do very much about a submarine or an aircraft. A tanker on that station is the most valuable and most helpless object in the ocean. The escorts circling her are the only reason the carriers a hundred miles away could stay where they were. It is not a line in any despatch, and it is the difference between a fleet that can fight off Okinawa and a fleet that has to go home to refuel.

A New Flag, and an Emperor's Voyage

Avon was paid off and placed in the Reserve Fleet after the war, before being sold to Portugal in 1949 and recommissioned as NRP Nuno Tristão.

The name she was given is not a neutral one. Nuno Tristao was one of Prince Henry the Navigator's most trusted captains, and in the 1440s he took a caravel further down the coast of West Africa than any European had gone: he named Cape Blanc for its white sand, reached Arguin Island and the Gambia, and opened a stretch of coast that Portugal would hold for five hundred years. He was also, and this is not incidental, one of the very first Europeans in the Atlantic slave trade. His orders in 1441 were to bring back captives for questioning, a skirmish produced ten prisoners, and within a few years Arguin was the staging post from which enslaved people were shipped north to Portugal. He died in 1446 up an unnamed river beyond the Gambia, killed with eighteen of his men by poisoned arrows when they took the ship's boats inland; five of the crew got the caravel home.

There is a long and uncomfortable line running from that man to the ship that carried his name, and it happens to run straight through this series. It was the Royal Navy that spent the better part of sixty years from 1808 trying to shut down the trade Tristao helped open, at a cost set out in the article on HMS Delphinium. A hundred and forty years after that campaign ended, a British-built frigate was sold to Portugal, given the name of one of the trade's founders, and sent to the same coast.

She went on to serve the Portuguese Navy for over two decades, including a rather unusual duty in 1959, transporting Emperor Haile Selassie of Ethiopia on a state visit from Bayonne to Portugal, and later supported Portuguese marine operations in Africa during the colonial conflicts of that era.

What she did there was not ceremonial. Portugal fought to keep its African colonies from 1961 to 1974, and Nuno Tristao was part of the naval effort: refitted in 1959 with her Hedgehog taken out, her 4-inch gun moved forward and a pair of Squid mortars fitted, she went on to support Portuguese marines ashore. In 1964, during Operation Trident, the Portuguese mounted a major combined operation across a group of islands, with helicopters flown from ships, amphibious landings, air strikes and naval bombardment led by the destroyer Vouga, and Nuno Tristao served as the central command post for the whole thing. A ship built on the Tees in 1943 to protect Atlantic convoys spent 1964 anchored off West Africa as the headquarters of a colonial counter-insurgency. Portugal lost that war, and the colonies became independent states within two years of it ending.

She was finally decommissioned in 1970 after 21 years of Portuguese service and scrapped in Lisbon in 1972, closing out a career that had carried her from the North Atlantic convoy routes to the Pacific and finally into service carrying an African emperor on a state visit.

Add the two halves together and her record is a strange one to summarise. Twenty-one years under the Portuguese ensign against six under the White, and in those six she escorted North Atlantic convoys out of Londonderry, pulled a hundred and twenty-three people out of the Indian Ocean six days after their ship went down, and screened the tankers that kept a British fleet fighting off Okinawa. She was delisted in 1970 and broken up at Lisbon in 1972, twenty-nine years after she was launched. Not a bad total for a cheap escort designed to be built quickly and not expected to last.