Memorial to those lost on H.M.S. THETIS in Mynwent Maeshyfryd Cemetery, Holyhead

June 1, 2024 marks the 85th anniversary of the tragic loss of HMS Thetis in Liverpool Bay.

In 1939, just weeks before the outbreak of the Second World War, the submarine HMS Thetis embarked on her maiden voyage. Departing from Cammel Laird, Birkenhead, she headed into Liverpool Bay for her first full sea trial. Unusually, there were 103 men on board, surpassing the standard crew complement by 50 individuals.

Those onboard included Naval observers, shipbuilder employees, caterers, and a Mersey Pilot. Tragically, during the initial test dive, an incident occurred with the forward No. 5 torpedo tube. As a result, the first two compartments flooded and the submarine’s bow became firmly entrenched in the muddy seabed.

Regrettably, only four men were able to escape, while the remaining 99 were trapped within the vessel, losing their lives.

Eventually, the submarine was raised, and the bodies of the deceased were recovered. Forty-four of these brave souls found their final resting place in a mass grave at the Maeshyfryd Cemetery in Holyhead.

Memorial Service

This year on the 85th Anniversary of this disaster members of the Merseyside Branch of the Submariners Association along with colleagues from the Wallessy Branch of the RNA will pay tribute to those lost at the HMS Thetis Memorial in Maeshyfryd Cemetery, Holyhead.

The Story of HMS Thetis (11T)

Shortly before 10 A.M. on June 1st 1939, His Majesty’s Submarine Thetis left Birkenhead under the command of Lieutenant Commander G.H.Bolus (RN). The principal purpose of the day was to make a diving trial. This was to be Thetis’s first venture as a submarine proper.

She had on board 103, fifty more than her normal crew. Of the extra fifty on board 8 were Naval Officers some commanding their own Submarines anxious to see the performance of this new class of Submarine. The others were Electricians, Engine Fitters, and Ship Fitters employees of Cammell Laird and Vickers Armstrong. There were two employees of a catering firm on board for the reception that normally follows the sea trials, and finally the Mersey Pilot.

Five hours later she was lying, sunk, 160 feet down, with her bows stuck in the mud. Although only 38 miles from land, 99 lost their lives, only 4 survived.

Two months earlier she headed out to sea for her first sea trials for engine and steering. During these trials the steering gear was found to have been connected the wrong way round.

When ordered to go to starboard she would swing to port. It seemed strange that acceptance machinery tests, supervised by Admiralty overseers, should have failed to detect so obvious a mistake.

It had been intended to carry out a diving trial in the Gare Loch, the traditional site for all such proceedings in the Clyde area. However, during the initial test of the hydroplanes they jammed in the “hard to dive” position. Despite the efforts of crew and Cammell Laird staff on board it could not be shifted. So the trials were postponed.

Liverpool Bay

As HMS Thetis headed out to Liverpool Bay she was headed by the Liverpool Screw Towing and Lighterage Company’s tug Grebecock to act as escort during the trials. It was also the duty of the tug to take the passengers from Thetis before she commenced her first dive. At 1.30 p.m. the tug received a signal from Thetis that all passengers had decided to remain on board Thetis and that the dive would commence.

At 2 p.m. sharp there was a “whoosh” of the air rushing out of Thetis tanks, which could be clearly heard by the crew on board the tug, Thetis had opened her main vents.

For the next 50 minutes the crew on board Grebecock watched the Thetis disappearing slowly below the surface in what was a dive in slow time. She had her bow down a slight angle and appeared to have difficulty getting below the surface then at 2 minutes to 3 p.m. she went down suddenly.

What happened on Thetis was a series of circumstances that would give one to believe that she was doomed from the start. When Lt. Cdr. Bolus ordered the dive it was found that she was light and needed more weight forward. This would entail taking more water on board. It was decided to check no 5 and 6 forward tubes which should have been filled with water to effect the ballast in the absence of torpedoes. The bow cap out of which the torpedo leaves the submarine is opened to let in water if the tube is to be flooded for ballast.

However, it is obvious that the rear door of the torpedo tube into which the torpedo is put would have to be closed, otherwise the whole submarine would very quickly flood. On this rear door there are small holes that can be opened by a lever. When this lever is opened the water in a controlled manner will spill out if the tube is full. If no water drips out then it indicates that no or at least very little water present in the tube.

The rear door can then be opened.Unfortunately for HMS Thetis during the painting and enameling these inspection holes did not seem to have been plugged before enameling and were painted over creating a seal in the inspection plugs. It was this one simple factor that was to have dire consequences for HMS Thetis.

Those responsible for controlling the dive could not understand why she would go below the surface. Although the paper work showed no 5 and 6 tubes were filled with water as part of the trim procedure, it was decided to test no 5 tube. The rear inspection lever was opened for inspection but only a very small drip of water escaped indicating very little if any water present in No 5 tube. No one was to know that the holes in the inspection hatch were stuffed with paint. It was decided to opened the rear door of No 5 torpedo tube. It is unfortunate that at this stage no one was aware that the bow cap of no.5 tube was open, flooding no. 5 tube. The lever to open the rear door of no.5 tube was pushed to open, but stuck before getting to the open position. Extra manpower was needed before the lever was finally with great difficulty pushed to the open position. With a tremendous gush of sea-water the men were knocked off their feet as the compartment quickly filled with tons of water, flooding the forward compartment. This sudden increase in weight forward forced the bow of Thetis further down in the water. At the same time more power had been applied to the engines and the angle of the hydroplanes put to “hard dive”. This combination of events had the immediate effect of sending Thetis to the bottom uncontrolled. The crew in the forward compartment struggled to close the hatch between compartments, but one of the locking bolts caught between the hatch and the hatch seating.

The impact of Thetis hitting the bottom, the lights failing in the forward compartment, and the water tight hatch stuck, forced the men to abandon any further attempt to free the hatch. They scurried for safety into the second compartment. Unbelievably the same faith was to happen with the second compartment hatch. Both compartments quickly flooded. They did however secure the hatch leading into the third compartment from the tons of seawater entering Thetis through the No 5 Torpedo Tube.

Thetis had two escape chambers one right forward and the other right aft, she also carried sufficient Deep Sea Escape Apparatus (D.S.E.A) for all 103 on board. She also had sufficient air on board for 36 hours. However, as Thetis had twice the number on board this was now reduced to 18 hours. All power to the engines were cut as Thetis settled on the bottom 160 feet below the surface and unknown to anyone 1 mile away from her escort on the surface, who by now was convinced something had gone wrong with the dive.

Thetis was to surface after 15 minutes and commence another dive. The escort tug realizing the time for Thetis to surface had long passed sent a signal to this effect to the shore support. Unfortunately the tug was not equipped for such an emergency nor was she capable of holding her position and had drifted in the strong current some 4 miles from the position Thetis lay. The Thetis and her position was lost and darkness closing in.

On board Thetis it was decided to empty the after tubes which would have the effect of raising the stern. The Thetis was 270 feet in length so it would rise well out of the water that was 160 feet at that time. Having pumped the after tubes the stern of Thetis did rise until the stern of Thetis was in effect sticking 18ft out of the water. Unfortunately, it was now dark and Thetis was 4 miles from the search area. The after escape hatch through which any escape attempt was to be made was 20 ft below the water line. No escape attempt could be made until it was established that there was a surface craft above to retrieve the escaping crew. All that Thetis could do was wait. It would be a long night.

A Long Night Ahead

All throughout the night surface craft searched frantically for any sign of Thetis. One hour after daylight a searching plane noticed a black object sticking out of the waterand finally confirmed that HMS Thetis had been found, the time was 0745, 18 hours since her dive and at the estimated limit that men could survive in Thetis. Conditions on board Thetis were extreme the men were very weak due to lack of oxygen.
All on board would be suffering from headaches. Surface craft rushed to the area where Thetis was sighted and immediately hammered on the hull of Thetis to let her know help was at hand.

It was time for an escape attempt. This would require the use of the breathing apparatus and entering the chamber, which would be filled with seawater. The hatch could then be opened for the escape 20 feet up to the surface.

The first attempt resulted in the death of the two men most probably due to their weak condition and mental state. The chamber was quickly drained and the bodies of the two men removed. Two more attempts were made with 2 officers, a leading seaman and a civie from Cammell Laird. These two attempts were successful and the 4 men made it to the surface.

In the meantime hawsers had been successfully secured to Thetis and things began to look better although the carbon dioxide concentration on Thetis would by be above normally accepted fatal density. It may have been at this point that things would begin to go badly wrong.Most of the remainder on Thetis were by now to weak to perform the necessary operation of securing the hatch in the escape chamber. It was certainly the last attempt to escape that caused for the second and final time two hatches to be opened at the same time. It will never be known how or why but at this last attempt the sea flooded the Thetis. Within seconds all occupants of His Majesty’s Submarine Thetis succumbed to the abrupt rise in the concentration of carbon dioxide that the rapid increase of pressure instantaneously caused. Long before sufficient water had entered Thetis to bring about the struggle and fight against drowning, the merciful gas had quietly and quickly killed them all, many of them while they slept.

The tons of water that flooded HMS Thetis put tremendous strain on the hawsers securing the stern of Thetis on the surface. It proved too much of a strain and the hawsers parted. HMS Thetis disappeared below the surface and finally rested on the seabed of Liverpool Bay.

It would be three more months and many attempts before HMS Thetis was finally raised and beached. But not before another life was lost, this was a diver who suffered with the bends during a recovery attempt. This brought to 100 the number of lives that were lost. When the bodies were finally recovered from Thetis they were buried in a mass grave at Holyhead

HMS Thetis Captain, Lt.Cdr. G.H. Bolus, was buried at sea.

HMS Thetis was salvaged, repainted and renamed HMS Thunderbolt. She also perished at 8.54 a.m on the 14th March 1943. She was depth charged and sunk by the Italian Sloop Cicogna. The Submarine that was first Thetis and then Thunderbolt rests 3,000 feet down in the pitiless waters of the Mediterranean.


W E ALLEN, Leading Telegraphist, HMS Thetis
T ANKERS, Vickers-Armstrongs Ltd.
J I ARMSTRONG, Assistant Electrical Manager, Cammell Laird & Co. Ltd.
W H ASLETT, Admiralty Overseer
F BAILEY, Admiralty Overseer
T BAMBRICK, Stoker, HMS Thetis
W G BATH, Caterer
F B BATTEN, Leading Signalman, HMS Thetis
W B BEATTY, Caulker, Cammell Laird & Co. Ltd.
G H BOLUS, Lieutenant-Commander, HMS Thetis
F R BRESNEN, Engine Fitter, Cammell Laird & Co. Ltd.
S BROAD, Electrician, Cammell Laird & Co. Ltd.
R S BROOKE, Leading Stoker, HMS Thetis
W BROWN, Engine Fitter, Cammell Laird & Co. Ltd.
A W BYRNE, Engine Room Artificer, HMS Thetis
H CHAPMAN, Lieutenant, HMS Thetis
A G CHINN, Electrician, Cammell Laird & Co. Ltd.
G P CORNISH, Chief Petty Officer, HMS Thetis
J COSTLEY, Able Seaman, HMS Thetis
H T CRAGG, Vickers-Armstrongs Ltd.
J CRAIG, Stoker, HMS Thetis
A CRAVEN, Ship Fitter, Cammell Laird & Co. Ltd.
J C CREASY, Engine Room Artificer, HMS Thetis
S CROMBLEHOLME, Able Seaman, HMS Thetis
R W CROUT, Shipyard Manager, Cammell Laird & Co. Ltd.
D CUNNINGHAM, Leading Stoker, HMS Thetis

H J DILLON-SHALLARD, Chief Stoker, HMS Thetis
E GISBORNE, Admiralty Overseer
R D GLENN, Commissioning Engineer, HMS Thetis
T T GOAD, Petty Officer, HMS Thetis
C T W GRAHAM, Telegraphist, HMS Thetis
L E GREEN, Stoker, HMS Thetis
J GRIFFITHS, Engine Fitter, Cammell Laird & Co. Ltd.
W L HAMBROOK, Leading Seaman, HMS Thetis
C J S HAMILTON, Electrician, Cammell Laird & Co. Ltd.
G A HARWOOD, Leading Telegraphist, HMS Thetis
R G B HAYTER, Commander, Admiralty Overseer
C M H HENDERSON, Lieutenant
A A F HILL, Admiralty Overseer
A G HILLS, Stoker, HMS Thetis
W T HOLE, Stoker, HMS Thetis
R HOMER, Engine Fitter, Cammell Laird & Co. Ltd.
J A HOPE, Petty Officer Telegraphist, HMS Thetis
C W HORNE, Admiralty Overseer
H HORSMAN, Admiralty Overseer
H G HOWELLS, Engine Room Artificer, HMS Thetis

G H DOBELLS, Caterer
D N DUNCAN, Brown Bros. & Co. Ltd.
A H DUNN, Stoker, HMS Thetis
H ECCLESTON, Engine Fitter, Cammell Laird & Co. Ltd.
J S FEENEY, Leading Stoker, HMS Thetis
H W E FRENCH, Engine Room Artificer, HMS Thetis
R N GARNETT, Lieutenant Commander

Unyielding in his pursuit of salvage, Petty Officer HOPPERDUE epitomised bravery and dedication. Tragically, on 23rd August 1939, while courageously attempting a recovery, he fell victim to the bends, paying the ultimate price for his commitment. His sacrifice serves as a reminder of the profound risks divers face in their perilous missions. We honour and remember Petty Officer HOPPERDUE, a true hero who gave everything for the call of duty.

The 4 survivors were

W C ARNOLD, Leading Stoker, HMS Thetis
Captain H P K ORAM, HMS Thetis
F SHAW, Engine Fitter, Cammell Laird & Co. Ltd.
Lieutenant F G WOODS, H M S Thetis


The Submariners Association is an association of serving and veteran submariners which seeks to maintain the special bonds of friendship, loyalty and comradeship, together with a pride in the Submarine Service, formed during service in HM Submarines.