"November 1925" "Britains biggest most advanced submarine the M1 has vanished without trace" "Sixty-nine men are missing presumed dead" "An air of mystery surrounds the tragedy" "It was peace-time The M1 was on a routine exercise" "How could such a Iarge powerful submarine just disappear" "For three-quarters of a century shes been missing her location unknown her loss unexplained" "But now at last she is ready to share her tragic secrets" "july 1 999" "A small dive boat the Portree" "leaves plymouth Harbour on a mission to solve the M1 mystery" "A storm is brewing in the english channel but this is the one week of the year when the tides are ideal for diving" "On board is a highly experienced team at the cutting edge of diving technology" "They have just seven days in which to work out what happened to the sixty-nine men of the M1" "TheyII be guided and advised by expedition leader Richard Larne" "Hes Britains top shipwreck archivist and an ex-Navy diver himself" "Hes been searching for the M1 for the Iast fifteen years haunted by the tragedy" "I spend my entire life investigating shipwrecks nowadays and this is one that caught my imagination mainly because its such a Iarge vessel it was lost in such strange circumstances" "No conclusive proof as to why she sank and its just something that has obsessed me if you Iike all these years" "I know its a Iong time ago and that the survivors of relatives of the M1 will now be in their 60s 70s 80s but nevertheless its important that I think that they know what happened to their loved ones" "The M1 was meant to be the ultimate weapon powerful enough to end the First world War at a stroke" "A submarine battleship a hundred metres long weighing two thousand tons and fitted with its own massive artillery gun" "But she took so long to build and equip that the war was already over by the time she finally came in to service" "Instead the Navy sent her on a peace-time tour of the Mediterranean to flaunt her mighty gun" "It was capable of shelling targets twenty miles away and although it never fired a shot in anger it had a powerful deterrent effect reminding friend and foe that Britannia still ruled the waves" "On the 1 2th November 1 925 the M1 took part in a major naval exercise in the english channel" "It was designed to test her effectiveness at hunting down enemy cruisers" "The exercise began at 7 oclock in the morning under grey skies off the Devon coast" "At 728 am the crew of the M1 reported sighting one of the cruisers and went in pursuit" "A minute later they slipped beneath the waves and were never seen again" "The M1 was last sighted about twenty miles south of plymouth but her exact resting place has always been a mystery" "The areas a naval graveyard" "The english channel has more shipwrecks per square mile than anywhere else in the world" "The only way to tell them apart is by sonar imaging" "Richard has spent fifteen years eliminating different wrecks and is now confident he knows the location of the M1" "But hes followed so many false leads he doesnt want to get his hopes up until he sees definitive proof" "Behind the boat a sonar tow-fish packed with electronics is bouncing signals off the sea-bed seventy metres below" "A visual trace appears on the screen and any unusual object will stand out" "But so far theres nothing" "Kevin Gerr is the dive leader on the Portree" "His first job is to locate the wreck and he needs the boat to steer a steady course for the sonar to find its target" "But up on the bridge the skipper is fighting the wind and sea" "The weather is deteriorating precise manoeuvring is impossible" "For three frustrating hours the boat makes pass after pass without success" "To make matters worse a trawler arrives and wants to fish on the same spot" "Fishermen are attracted to wrecks because where theres a wreck theres always fish" "But if there is a wreck below where exactly is it" "The tow-fish continues to hunt out its prey" "In desperation Kevin widens the search pattern and is finally rewarded with the picture hes been looking for" "Theres a Iarge submerged object with a Iarge sticking-up bit in the middle" "Thats right The conning tower" "unless Im extremely mistaken thats a submarine" "Awesome" "Thats great Great congratulations" "Its pretty good isnt it Youve got a nice trace on now Look at it" "Yeah lovely" "There is definitely a submarine below" "But is it the M1" "The only way to be sure is by diving it" "But the search has run way over schedule and the weathers getting worse" "It would be too dangerous to enter the water in this swell" "The next morning brings gaIe-force winds" "For three long days the Portree can do nothing but stay in dock and wait for the storm to pass" "These are the hazards of wreck hunting in British waters" "hello hello good morning" "could I speak to Mr Davis please Yes speaking" "Oh hello Mr Davis this is Richard Larne calling you from plymouth" "Yes Just telling you that weve safely received the painting you sent on which is absolutely splendid and I wonder if you could tell me a little bit about the background because I believe theres a story about it" "There is a story Word of Richards expedition has spread and new information is surfacing" "Hes been sent a picture of the submarine the only one in existence" "It seems it was painted by a member of the crew" "Indeed What do you know about the artist" "I dont know anything about the artist at all other than the fact that he is supposedly the man who left the ship on the morning it sailed on these exercises" "I see well we have found a page of the daily Mirror of the day and we have a picture of a number of the men who were lost on board but also there is a picture of the only survivor" "Yes able seaman JW sales" "And it says that he remained ashore on account of the death of his mother missing a trip for the first time in two and a half years" "So I guess that able Seaman sales must have been the artist of your lovely painting Yes actually as youre saying that I can really feel a shiver going up my spine" "really Yeah well there we are" "sales received the news about his mother just three hours before the M1 set out" "As he left the Iast thing he grabbed was his painting" "Its quite remarkable to think that this is probably the only surviving relic of the submarine the M1" "And of course had the seaman who was the artist received that telegram four five six hours later it may well have been all too late and this painting would have gone down with all hands" "Lets hope in fact that we find the submarine on the sea-bed and its looking something like that" "The weather has improved dramatically" "The english channel looks more like the Caribbean" "Conditions are now perfect for diving" "But theres only three days left for the team to gather the vital evidence they need" "Back at the site they kit up" "Theyre each carrying a hundred and fifty pounds of equipment which will help them cope with the enormous pressures below" "finally the three divers start their descent" "They have no idea what theyll find when they reach the sea-bed" "In 1 925 the M1 was considered far too deep to dive" "But the Germans had a revolutionary suit that could work at such depths" "In a desperate bid to rescue the crew the suit and a team of divers were shipped to plymouth" "Some officials were worried about the old enemy getting a cIose-up look at a state of the art British submarine" "But the German divers found nothing in the cold dark waters" "AII hope of rescue was officially abandoned" "Today technology has moved on but at over seventy metres the wreck remains out of reach for most divers" "So Kevin and his team are using a sophisticated tri-mix system" "Instead of breathing compressed air they carry three different gases and mix them as they swim deeply" "below forty metres oxygen and nitrogen become toxic" "But by increasing their intake of helium the divers can expand their lungs and go much deeper" "Its a dangerous process" "If they get the mix wrong theyII black out" "finally out of the gloom emerges a ghostly site the decaying remains of a submarine a huge steel coffin seventy-four metres down unseen for seventy-four years" "Kevin and the team have arrived towards the back of the wreck and are making their way forward" "Theyre looking for clues filming anything that can positively identify this as the M1" "Theyre swimming against the clock" "Even with their tri-mix gases they have only twelve minutes on the wreck" "Theyd like to find the great gun but thats at Ieast a hundred feet ahead of them and they won get that far" "But they do manage to reach the central control tower known as the conning-tower one of the most distinctive features on a submarine" "On the surface Richard can only wait" "Having been a diver for fifty-two odd years myself" "Id like to be down there with them but of course I was always a compressed air diver and never a mixed gas diver like these youngsters are" "still if I was twenty years younger" "I suppose Id be diving rather than just sitting up here top-side waiting for them to come back and tell us what theyve seen" "After a lengthy decompression stop the divers return in high spirits" "For Richard its the moment of truth" "Hes about to find out if his long search for the M1 is finally over" "There it is" "See a Iot of the outer casing is gone" "Oh the submarine is wide open See the" "Yeah thats the frames" "I was trying to get you to come up light on top" "Put a light in to the hole" "Off to the side a little bit I had to stop I was getting beaten by the current Yeah Thats good footage though" "Its lovely Youre going forward towards the conning-tower" "Kevin spools on to the end of the tape" "If theyre going to get a positive identification its most likely to come from the conning-tower" "Theres step holes there Theres the squares where the people step up in to it Thats one of the masts there" "Thats looking up Youve got that rake angle like that Thats the front there" "This is the back This steps down" "Youve got that step down like that" "So were actually - what we were doing we were looking up like this up on to there That shot there is like that now going up in to there So thats the rake rake of the tower yeah" "Come back a shade And theres - theres some foot steps over there you see Yeah" "And if you can freeze it in a minute when you get to the railings" "Weve got a photograph of the submarine Looking up at the conning-tower" "It doesnt - yes it does Does it not show it" "No it doesnt,Doesnt show it the same on there" "But then of course we dont know how we dont know how often the submarine had been modified" "well weve got the step holes These three still get these three holes Theyre all there,Yeah" "exactly the same Step holes There,There they are" "One two three Yeah Its the M1" "Theyre small but unique" "These three step holes are definitive proof that this really is the wreck of the M1" "Ive been looking for this submarine for fifteen odd years and now having finally seen evidence of it its a strange feeling Its the end of an era in a way" "The wreck is quite beautiful really eerie I suppose" "Now of course weve got to work out how on earth she sank and why she sank" "In the weeks following the tragedy the admiralty set up a Board of Inquiry which took three months to prepare its report" "It focused on a Swedish cargo ship the SS Vidar which had been in the english channel at the same time as the M1" "Her crew had reported hearing a couple of loud bangs but thought nothing of it and sailed on" "It was only when they docked and the ship was examined they realised they might have hit something big" "There was signs of collision damage to the ships bow and traces of the same naval issue paint used on the M1" "The official investigation came to the most obvious conclusion the M1 sank after colliding with the SS Vidar" "But serious doubts have always remained" "Seven years before a British war-ship had collided with a similar sized submarine" "Its bow had been virtually destroyed" "By comparison the damage to the SS Vidar was slight" "How could she have dealt such a devastating blow to the M1 without her crew even realising" "The investigators of 1 925 couldnt answer this question because they couldnt examine the key piece ofevidence the wreck of the M1 itself" "Todays investigators have no such problems" "With the aid of modern diving technology they have all they need to survey the wreck" "Its hard work so they conserve energy when they can" "Its day six and the Portree has arrived back on site with two new passengers" "Keith Dickson is a senior marine accident investigator" "Its his job to work out exactly how and why ships sink" "bill EIIison is a retired submarine commander drafted in by Richard to provide more technical expertise" "Time is running out and theres another problem" "The Portrees main line to the wreck has been cut by fishermen angry that the divers are disturbing their waters" "Hours of hard work have been undone by this act of vandalism" "The team now has to reset its moorings" "By the time the line is back in position and the Portree is over the wreck again the currents have increased and the tidal window for diving has passed" "The divers will have to wait another six hours for the next opportunity" "They amuse themselves as best they can" "I believe your shot is somewhere near the conning-tower area" "Is that right should be,Yeah" "well if you come up on to the conning-tower" "As the sun sets Richard briefs Kevin and the divers" "Shine the light in to it and then work your way along the centre" "line of the submarine" "Having identified the wreck as the M1 they now need to find evidence of a collision" "And then further along youve got a hatch which you are going to have to spend a little time on" "well well try and shine down in all of those and video all of those Yeah" "If youve got time yeah Yeah" "The divers are hoping to cover more of the wreck this time" "Theyre carrying extra gas and they know their way around" "They go to the stern of the submarine and find the propellers still intact" "But they keep their distance from the lethal fishing nets" "They make their way forward searching for signs of damage" "The submarine is full of holes caused by corrosion to the thin outer casing" "But theyre looking for holes in the water-tight inner casing the pressure hold" "Moving on beyond the conning-tower for the first time they look for the great gun" "But theres nothing there" "The massive sixty ton structure that should be on the hull of the submarine is missing" "AII thats left is the circular mounting ring on which it wouId have sat" "The divers look around for the gun housing and find it nearby on the sea-bed" "But the barrel of the gun is nowhere to be seen" "And this is the gun laying off it,Yes" "Thats the gun laying off it Thats the gun" "This is part of - part of it bent over" "Its almost like a separate little sort of bridge thats fallen" "Yes yes dropped down,Thats another" "Theres some more of that" "Thats the fabrication that held the gun in place" "Its quite clean there isnt it Yeah its rust" "And thats the curve of the hull Thats the hull" "Yeah I tried to get Thats the sea-bed down there" "Yeah the of the keel that side And theres the" "Theres the mounting ring Ah theres the mounting ring" "Wheres the rest of the framework Thats the mounting ring there" "Its twisted It is" "Its twisted off the port The port" "The centre spigot has created it to go off" "Is that so Yeah thats been really twisted off hard Yeah" "Its taken both frameworks" "This is the first real clue" "The gun hasnt just fallen off over time but has been violently wrenched from the hull" "As the Portree heads home for the night they discuss the implications of what theyve seen" "That whole area there is not there any more" "No Its somewhere away" "The rest of it is a gently decaying wreck" "exactly Richard and I think youve just summed that up a gently decaying wreck all the way through" "Except for that evidence there" "That area there Thats right" "And if she - if this gun was hanging off dragging her off over on one side she could have gone to the sea-bed when the gun hit the sea-bed and took the weight off it she could have then just sort of settled upright again like that" "possible I think again it wouId be- it wouId be excellent if we can persuade the divers to go and have another look tomorrow in that area" "Need to look at that gun just a little bit more closely" "bill bill as a submariner how would the skipper of this submarine have found himself if suddenly a fifty-eight ton gun had been dislodged off his deck and was hanging off on the - on the side and he was now on the sea-bed" "as the divers have seen it today" "What - would that prevent him from blowing ballast and surfacing Yeah well certainly" "This whole huge compartment here is the" " is the heart of the submarine" "So lose that you lose pretty well everything especially in that" "So if we surmise then that the forward part of the submarine became flooded pinning it down there was no way of getting it up it could have been that life possibly survived in the rear end of the submarine" "With the expedition nearly over the mystery is beginning to unravel but they need to see more and time is running out" "In twenty-four hours the tides will change and diving will be impossible" "Tomorrows dive is critical to the investigation" "They wake to bizarre news" "AII week the plankton levels have been unseasonably high" "Theyve now taken on epidemic proportions" "A huge bloom is drifting through the english channel and its currently sitting over the site of the M1" "The divers test the water and their worst fears are confirmed" "The clear visibility of the past two days has gone" "leaving them struggling through a thick green soup" "Its too dangerous to return to the wreck until the plankton has died off but that could take days or weeks" "The team abandons the dive and with it their last chance to gather evidence" "Who would have believed that the conditions under-water could change so much from one day to the next" "Its a frustrating end to the expedition really" "Despite all this equipment weve been defeated by nothing more grand than plankton microscopic plankton" "Richard has reached a dead end" "He has found the M1 and is part way to explaining the tragedy" "But now hes run out of time and still has more questions than answers" "There does appear to have been a collision but there are no holes in the submarines pressure hull so why did she sink" "Whats happened to the gun barrel" "Was there any attempt to escape" "He reads and re-reads the files in the naval archives searching for any new clues" "There were unofficial reports at the time that claim the submarine had been having serious handling problems" "What if she was already in trouble before the collision" "For the moment Richard can only speculate" "Then just as it seems the mystery will never be solved the team has a breakthrough" "Keith Dickson the accident investigator has got access to a survey vessel for one day and has returned to the site of the M1" "This time there are no divers on board just a remote operated vehicle" "For detailed survey work the ROV is essential because it can stay down for hours sending live video pictures back to the boat" "In the control room an operator directs its every movement providing Keith with the cIose-up forensic evidence he needs" "A smaller ROV detaches itself from the main unit and begins its work slowly exploring the wreck" "Re-examining the hull they see something the divers missed a V shaped gash" "This hasnt been caused by corrosion but by impact with a sharp object perhaps the bow of the SS Vidar" "It looks like an angle of about seventy seventy-five eighty degrees Id say" "About thirty degree indentation Yeah" "The gash is further evidence of a collision but it wouldnt have been enough to sink her" "Theres still no sign of a hole in the inner-pressure hull" "well take a detailed look at the gun bay now I suppose" "Side to side" "Yeah I think well Oh" "What can we see down there" "finally the discovery theyve been waiting for" "The mounting ring doesnt sit on top of the pressure hull as they thought but passes right through" "Once the gun had been knocked off water would have shot down through this hole and flooded the central part of the submarine" "But that would be flooding in to the magazine area" "Or the shell room as they call it yes" "And then afore and after that magazine youve got water-tight buIkheads and doors but we dont know if they were open or closed" "Keith is the first person in seventy-four years to look directly in to the heart of the M1" "But he wont go further as the wreck is a war grave" "And this is the telegram Yes that the admiralty would have sent" "Yes The day after she was lost" "Thats it,Yeah" "It was splashed in the newspapers before it got" "As the survey continues at sea" "Richard pays a visit to Vera JeweII whose father died on the M1" "It wasnt very informative was it it just says No" "Morning stop letter following AdmiraIty Thats it" "Thats very heartless really isnt it" "Henry JeweII was an able seaman gunner" "The M1 was the first submarine hed served on" "And he was a worried man" "He told his wife he had grave concerns" "Shepperton man dies in M1 disaster" "It says of your father that he had no faith in the boat" "Yeah" "He had visited his home only the previous weekend from the Friday to the Monday" "Did he say anything much about the M1 when you last saw him when he was on leave" "He didnt say anything to mum but he said to his brother that he thought that was going to be his last weekend because theyd been on exercise and they just didnt think they were coming up again" "really Yes exactly" "He had that sort of premonition that he was possibly going to die" "Yeah And a number of the other crew had said the same thing" "They just didnt have any faith in her" "And did he say why they didnt why he thought it was unsafe" "It was the weight of the gun really" "He said to his brother at the time that the weight of that gun was too great for the boat" "It still makes you very angry doesnt it" "It does It does" "Because well they were just it hasnt been said but to me they were just experimenting and lives didnt mean a thing" "Thats what it boils down to doesnt it" "Back on the boat theyve made a chilling discovery" "Yes youre right It looks as if there is a hatch in that area" "Looks like a metal hatch of some description" "So at some stage thats been opened up" "Behind the conning-tower theyve found a major access hatch which is open" "Its so heavy it could only have been opened from the inside" "Those that survived the initial flooding must have tried to escape" "Opening the hatch" "It could be an extended ladder to get through the casing" "Its quite a Iarge hatch" "So I should imagine some mechanical means of opening it wouId be required" "Be pretty hefty to do it once youre in cold water and in a state of panic to open a bloody you know hatch weighing a quarter of a ton or something" "Thats right" "It would have been a desperate measure" "Without breathing apparatus the chances of survival were nil" "We understand Vera that the M1 probably didnt have any escape apparatus on board" "You dont know if your father ever mentioned anything that was provided to help them in anyway" "He said they were given tablets" "Given tablets What sort of tablets" "To swallow tablets to swallow" "What sort of tablets were these" "I presume they were poison arsenic" "really Yeah" "My word thats quite dramatic Thats it" "Ive never heard that story before" "well I suppose it was a quicker way of death than the oxygen being exhausted" "Right" "I mean really its offering the men a chance to commit suicide isnt it Yes Yeah" "Is that what you mean Thats it Yeah" "really Yeah" "Thats quite remarkable Yeah" "The ROV is being hauled out of the water" "Keith has all the clues he needs" "Its time to piece together the evidence and work out exactly what happened to the M1 and her crew" "The hydrodynamic test centre at Gosport is where all new naval submarines and ships are tested for seaworthiness" "scale models are used to replicate the movement of a vessel through water" "What we think now is that the Vidar made contact in this area came in contact above the pressure hull" "The test centre is where Keith does much of his work" "Today he has been joined by Richard and bil as they finally lay the mystery of the M1 to rest" "Gun support over to the port side" "And the gun mounted And then as it went out the kingpin which is under here went with the gun" "From there you would get serious flooding" "It was not really a serious collision" "No it was the effects after the collision that were serious" "It was a glancing glancing blow just on the very very high point of the - of the ship" "And we know that the damage was right at the forefoot the very front bottom part of the keel of the Vidar which meant that that was her maximum depth in the water" "The people trapped in the engine may or may not have had any communication but the first thing they would probably have done would have been to shut down the motors" "Indeed" "They would then I would have imagined stayed inside the submarine hoping for rescue" "Yes Thats right" "So I would imagine if these men had any idea of how deep they were on the sea-bed they might quickly have realised that they didnt have a hope in hell of ever getting out" "But Indeed" "But they surely would have stayed there for a day or two days or three days until they got desperate" "And of course the great gun whilst it was its strength it was also a weakness Indeed" "After a Iong debate" "Richard Keith and bill are in agreement" "Seventy-four years on the full story of her final moments can now be told" "At 729 the submarine dived for the Iast time" "The enormous weight of the gun made her top heavy and prone to overbalance" "She was in relatively shallow water for such a Iarge vessel" "So her crew would have had to blow their ballast tanks to force out water and bring her back to the surface" "But unknown to them the SS Vidar was bearing down on them at speed" "It was only a matter of seconds" "The Vidar hit the M1 twice" "One of the blows was to the gun barrel which would have knocked the whole gun mechanism off its mounting" "The submarine was in free-faII with its gun hanging off to one side and the barrel already detached" "They couldnt blow ballast as there was no air left in the tanks" "By the time she hit the sea-bed the nerve centre of the submarine was crippled" "Men in the aft sections were still alive but without power light or communications" "In a desperate bid to escape they allowed water through the bulkhead equaIised the pressure and opened the access hatch" "Their bodies were never found" "The Submariners Association ishoIding its annual reunion" "Three hundred veterans have gathered at the historic naval base in Gosport for an open air service" "Submariners are a special breed brave or foolhardy enough to spend months together under water in the most cramped conditions" "They call themselves a family and like any family they remember their dead" "After all the technicalities of recounting this ceremony today really brings it home that the whole thing is all about people" "To realise that those men made a genuine abortive fatal attempt to open the hatches to let the sea in and die in the attempt to me is just so sad So so sad" "As long as the M1 remained undiscovered on the sea-bed there was no real knowledge as to how she was lost" "Weve been able to write that final chapter and I think we have laid a great many ghosts to rest" "She was the greatest submarine of her age the most awesome weapon ever to have been sent to sea" "And yet she was powerless to save herself from the freak accident which destroyed her" "The motto of the submarine service is They Come Unseen" "The tragedy for the crew of the M1 was to die unseen" "The plaque left by the dive team sits on top of the hull a testament to the sixty-nine men who can now rest in peace"