A SPECIAL memorial to mark the 75th anniversary of the worst peacetime submarine disaster in the history of the Royal Navy will be unveiled on the banks of the Mersey on Sunday.
HMS Thetis sank on her sea trials in Liverpool Bay on June 1939 with the loss of 99 lives.
The warship was carrying twice as many men as she was designed to carry when she went down.
There were 53 crewmen, several engineers and observers from Cammell Laird – where the vessel was built – Vickers Armstrong and the Admiralty.
Sunday's ceremony will take place at River Walkway, Birkenhead at 1pm.
Thetis sank to the seabed on her very first dive. She was raised and salvaged a few months later and saw service in the Second World War, having been commissioned as HMS Thunderbolt.
She was lost with all hands in 1943 to become one of the few military vessels to have twice lost her crew.
Ben Whittaker, curator of port history at Merseyside Maritime Museum, said: "Through the night the crew worked doggedly to raise the vessel and were able to lighten the aft section enough to allow the stern to break the surface.
"The next morning four crew members, led by Captain Oram, escaped through a hatch using breathing apparatus.
"They were picked up by the HMS Brazen which had been diverted in response distress calls.
"Others attempted to escape in the same way but drowned when the hatch jammed. A cable was attached to Thetis, but this snapped and the submarine returned to the seabed.
"On Saturday, June 3, the Admiralty announced there was no hope of any further survivors.
"The submarine's unusually crowded conditions meant that the air would not have lasted long, causing those left on board to suffocate, poisoned by the carbon dioxide from their own breath.
"This tragedy prompted the introduction of the ‘Thetis Clip’.
Still used by all British submarines to this day, it ensures the torpedo tube doors can only be opened a small amount in case the tubes are flooded – this was in part what had caused Thetis to sink.”
Derek Arnold, chairman of the Liverpool Anchorage Club and son of Walter Arnold, one of the Thetis survivors, has been fundraising for a memorial to mark the 75th anniversary since last October.
Many of those who died were workers from local shipyards and fund-raising has been a community effort. Donations came almost exclusively from the general public, mainly from the Merseyside area.”
Free car parking has been arranged with Peel Holdings at Woodside Business Park. Toilets and refreshments will be available at Woodside Ferry Terminal.
As the floral tributes are laid at Woodside, lifeboats from Moelfre, Llandudno and New Brighton will be casting theirs on the water.