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15 October 2014
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Secret Training on DD (Swimming) Tanks. Preparations to retake Singapore

by John Leyin

Contributed by 
John Leyin
People in story: 
John Leyin
Location of story: 
Cocanada/Madras, India
Background to story: 
Army
Article ID: 
A1311652
Contributed on: 
29 September 2003

After playing our part in winning the Battle of the Admin Box, in Arakan, Burma – a battle acknowledged by military historians as one of the greatest defensive battles of World War II – my Regiment, the 25th Dragoons, pulled out of Burma to train on the once-on-the-secret-list, the DD (Duplex Drive) Sherman tanks, for the impending invasion of Japanese-occupied Malaya. These were the ordinary land Shermans tanks that had, with remarkable ingenuity, but rather basic technology, been adapted to float and make their own way in water. They could be launched from landing craft over three miles from the beach in any depth of water and independently steered to shore. Since practically the whole of the tank was below water level, these tanks were now virtually submarines.

The adaptation required to make these land tanks water-borne was that of a canvas screen, or skirt, fitted completely round the tank, which could be raised by compressed air being released into hollow rubber pillars. When fully raised this screen, extending from just above the tank tracks to above the turret, could be locked into position by elbow jointed steel bracing struts. With this modification, once in the water, all that could be seen of this 30 ton piece of armour was what appeared to be a cumbersome rectangular canvas boat, with a freeboard of about three feet. Supported in the hollow of its surrounding screen, most of the tank was below the water line, and was driven by two tank-engine powered propellers at the rear of the tank, at a speed of about 2 mph.

While water-borne there were, depending on the circumstances and conditions, two methods of steering. Once the tank had left the tank landing craft, at some distance from the shore – perhaps a mile or so – it would be steered by a tiller bar operated by the tank commander who, standing outside on the back of the tank, could see over the canvas screen with an unrestricted view. As the tank neared the shore, the tank commander would disconnect the tiller bar and, for obvious safety reasons when in action, then jump into the turret. Upon which the steering would be taken over by the tank driver in the hull who, by looking through his periscope, which had been specially extended to just above the top of the raised screen, would manoeuvre the vehicle to shore by using his steering sticks as he would normally. For the driver this, with the swell of the sea and his view-restricting periscope, was not the easiest of tasks even on the calmest of days.

As the tank came ashore, the canvas screen would then, from the inside of the tank, be collapsed, when it would fold itself in concertina fashion, into a neatly compacted unit of about a foot high all around the tank just above its tracks. And it then would assume its more usual role as a land tank.

As the tank tracks and undercarriage of these amphibious tanks would be completely immersed in water, it was of the utmost importance, before we undertook these exercises, to ensure that the tanks were made completely waterproof. This we did by sealing every potential water admitting area with softened pitch. But no matter how much attention we gave this vital job, water always leaked into the main hold of the tank, which was then pumped out by a bilge pump that had been incorporated as part of the system.

This bilge pump also had to cope with the water that splashed over the screen and into the tank, a hazard encountered when the tanks were being eased into the sea down the lowered ramps of the landing crafts, the ramps of which had to be precisely angled. Too steep a ramp angle, or too fast a descent on a correctly angled ramp, could result in a tank going straight to the sea bottom together with its crew. As it could too – even with a controlled descent on a correctly angled ramp – with a tank launched into a turbulent sea. Indeed, during the invasion of Omaha Beach by the American forces on D-Day twenty seven out of thirty two of these DD Shermans sank within minutes when they were launched too early into unfavourable sea conditions. Some of the crews escaped but many unfortunately drowned in their tanks.

As part of this training, we had to undergo the appropriate emergency escape discipline from a sunken tank, which included our using what was known as the Davis-type escape apparatus, a breathing apparatus similar to that used in submarine training.

The initial stages of this underwater escape training involved walking with one’s breath held, across the bottom of the deep end of the nearby swimming baths (of which the water was always a murky green and in need of change), while holding on to an underwater tethered rope that was stretched from one side of the baths to the other. Later, when this was mastered, we would carry out the same exercise while breathing through the full Davis-type escape apparatus, which comprised an airbag strapped to the chest, a mouthpiece, and a pair of nose clips.

The final stages of this underwater escape training took place on the beach in the shell of a Sherman tank that was situated at the bottom of an enormous watertight steel drum. This drum, which was about twenty feet in height and perhaps twenty five feet in diameter, had been specially constructed around this tank and had a steel ladder on its inside down which those being trained climbed to gain access to the tank’s interior. Welded to the top of the drum were two enormous yawning sea-water discharging faucets poised ready to disgorge themselves whenever so required. After each crew member, wearing his Davis-type escape apparatus, had seated himself in his appropriate crew position in this shell of the tank, the two faucets would be opened to send the gushing sea-water crashing down on to everything below them – on to tank and man – to simulate the effect of a sinking tank. And it was most effective.

As the water gushed down into the steel drum, it quickly rose and began to engulf the tank itself. At which, the escape procedure demanding strict self discipline, every crew member had to sit tight and not touch his escape apparatus until the last moment – when the rising water was chin high. Then and only then, with the water still rising, was he allowed to put on his nose clips and put in his mouthpiece through which, as the water covered him, he could breathe. And he remained thus until the faucets were turned off. Even for the experienced swimmers among us, sitting there waiting with the water rising rapidly, it was not a comfortable experience, for there was – if for instance one fumbled with part of the apparatus – no margin for error. For the non-swimmers among us it must have all been an unspeakably terrifying experience – increasingly more so as the simulation continued.

Once the water had risen to six feet or so above the turret, the crew, after sitting submerged for a few seconds, then had to make their escape – but in strict order, one at a time, since an every-man-for-himself exodus would have resulted in bodies being trapped in the escape hatches. In the turret, the tank commander, as he was nearest to the turret hatch, would exit first. And as he went he would tap the 75mm gunner on the shoulder to signal that it was now his turn. The 75mm gunner, as he was about to leave, would, in turn, tap the shoulder of his loader for him to get ready to go. In the hull of the tank, the driver and the wireless operator followed the same procedure, but through their own hatch. Sitting, waiting for that tap on the shoulder, and knowing that you had to rely completely on your colleague to fulfil this duty, in murky water with vision restricted to less than one foot, made the short wait seem infinitely long – again, especially for the non-swimmers.

Once clear of the tank, the crew members would float to the surface and then make for the steel ladder on the side of the containing steel drum.

Much as I loved the water and was a fairly strong swimmer, I did find my first experience of this simulated sinking tank exercise a little unnerving. Indeed, it was said, that one of the Regiment’s senior officers ‘declined’ to take part in this particular exercise. Whether this were true, I never found out.

Since our tanks were still on the secret list, all our training was undertaken well away from prying eyes, on a spit off Cocanada (now Kakinada ) which was about 300 miles north of Madras and which was now our established base.

Every morning as we were ferried out to the spit, where our tanks had been secretly shipped, we were greeted by a sight that gave rise to much amusement. For as we chugged our way past the well populated village, situated along the water-front above us, there were dozens of lined up squatting male villagers who, with bare backsides facing us and balanced precariously on the water-front wall, were defecating straight into the sea, some thirty feet below. The reaction by the more vociferous among us to this apparently not unusual custom of the villagers, was, to say the least, clamorous, but all in good humour. However, the performing villagers, in a natural if not questionable dignified way, ignored any ribald remarks that were made, and continued with their business. And we chugged merrily on our way.

Once on the spit, we wasted no time in getting down to our training.

Although the DD Shermans we were to train on were the tanks intended for our use in actual combat, we also had one or two British Valentine tanks – similarly adapted for ‘swimming’ – which were only for training purposes.

The Valentine had a crew compliment of only three: the tank commander and the gunner in the turret, and the driver in the hull. Unlike the Sherman where the driver sat in an upright position, the driver in the Valentine was laid back with his legs stretched out in front of him. But whichever tank was used, I found our amphibious training tremendously exciting – although I did, on one occasion, have a very worrying experience.

On one Valentine training session, after I had taken over the steering from the tank commander, about a quarter of a mile offshore, I noticed that much more water was leaking in than usual. It was swirling around my feet and getting deeper and deeper, and the bilge pump, working as hard as it could, was obviously not able to cope. Some of the tank’s waterproofing had undoubtedly come adrift.

The tank commander and the gunner, being in the turret, were not aware of our predicament. I could have informed them over the intercom, but not wishing to give the impression that I might be making too much of it all, decided not to – there was nothing they could do about it anyway. So putting my foot down hard on the accelerator and, praying, with my eyes glued to my periscope, I continued flat out for the shore. And I made it – just. For the water was sloshing around my ankles as we hit the beach.

Being one of the first to finish our amphibious training, I was put in charge of what we called a dhoni – a long, narrow boat used, I believe, by the local population for fishing. To these dhonis we had fitted an outboard motor that could be swung up to rest on the stern, clear of the sand, as we beached them. There were, as far as I can recall, four or five of these dhonis in the Regiment, and we used them to cruise around the tanks training in the water, to pick up survivors of any tank that went down. This dhoni duty extended to ferrying the squadron trainees out from Cocanada, along the ‘bum run’, to the spit in the morning and ferrying them back in the evening.

The spit, usually because of the distant sea mist, could not be seen from Cocanada and, since none of us in charge of the dhonis had compasses, the procedure was to head straight out from the water-front and to keep going until the spit came into view, and then change course to head for it. Although on many occasions this rather coarse navigational method did produce its disconcerting moments before the spit finally came into view, fortunately we were never far off course.

The trip from Cocanada, finishing with a run up to the beach, with the outboard engine cut and its propeller tilted clear of the sand as the dhoni ploughed its way up the spit’s gently sloping beach, where the squaddie passengers would disembark, was a delight. As indeed it was too when, later and alone, I cruised around the ‘swimming’ tanks in the usually calm Bay of Bengal with the balmy air caressing my all but naked body.

Another delightful experience I found was to observe the phosphorescent effect of the agitated sea water, which at night was a remarkable sight, especially when, in the pitch blackness, I ran my hand vigorously through it to splash it around. For the disturbed water would appear to become ignited with brilliant cascades of sparks as the splashes rained down upon it. Indeed, engaging in this delightful activity, with countless stars speckling the jet blackness above, I found, for the first time, that night guard duty did have its compensations.

Although we had been trained in the use of the Davis-type escape apparatus, we did not wear it, or any part of it, while training on the tanks. Presumably it was thought that there was little danger of a serious mishap in our non-hostile training conditions. The wearing of it was thus reserved for the time when we were to embark for actual combat.

We did, however, wear an inflatable lifebelt around the waist. And on one occasion when we were practising entering the water down the ramp of a tank landing craft that was hove to at some distance from the shore, one of the tanks entered the water too fast and, instead of levelling out, went straight down to the sea bed. Some of the crew bobbed to the surface almost immediately, while others, depending on their position in the tank, took a little longer. But there was no sign of the driver. And with his having no breathing apparatus this did not augur well for his safety.

Perhaps the hatch in the hull had stuck or perhaps the driver, although having successfully completed his escape training, had panicked, finding that having to deal with such a frightening situation in a real sinking tank was immeasurably more demanding than it was in training. But before anybody could gather his wits regarding what action to take – which was limited anyway– the driver broke surface. Gasping for breath and obviously shaken by the experience, he recounted his plight. Apparently, as his tank went under, he tried to escape through his hatch but, hampered by his inflated lifebelt, this proved impossible. With the tank now completely submerged the tapes of his lifebelt then got caught on something. Desperately he tried to undo them and, after one or two unsuccessful attempts, managed to free himself. Leaving the lifebelt behind, he then swam to the surface.
Our training on these amphibious tanks was now at an end. It was obvious that we were to be part of a sea-borne invasion of a Japanese occupied territory. But where and when that was to be, we, the rank and file, did not know. Nor did it appear to worry us at the time, for our training had been not only intensive but also unusual and, to many of us, so interesting and adventurous that it completely occupied our minds. It had not been without its dangers, of that there could be no doubt, but it had been, after all, only training. And so for most of us, since there had been no enemy attempting to inconvenience us, it had been an experience we had, on the whole, enjoyed.

But having experienced in the Arakan the object of our previous training – the horrors of actual combat – the object of the training which we had now completed somehow did not register so deeply on our minds, or at least on mine, as perhaps it should have done. Perhaps this was simply because we took every day as it came … I cannot say. Certainly I did not want to go to war again, and the seemingly inevitability of the prospect of my having to hovered only fleetingly on the periphery of my mind.

Our new draft who had not yet been in action, and who had no idea of what it entailed, were, however, raring to go, with all the enthusiasm that only such naiveté could bring. This did on occasions make me think ‘If you only but knew.’ But it was only a passing thought.

During our training we became very much aware that, once in the water, our DD Shermans were extremely vulnerable – since it was all too apparent that they could be sunk even by small arms fire, to say nothing of the effect that the flying shrapnel from near miss exploding shells or mortar bombs would have on them. And once the tank supporting canvas screen was ripped apart beyond the bilge pumps power to cope with the consequent inrush of water, the tank would sink – and sink quickly.

There was also the danger of a too great a swell of water being scooped in, over the top of the tank, by the plunging relatively flimsy canvas screen. For the DD Sherman had no bow as such to assist its passage into and through the water. It was, once in the water, just a floating oblong canvas vessel with a freeboard of only about three feet. We had not heard of those twenty seven DD Shermans that had sunk within minutes in the heavy swell during the Omaha landing on D-Day. Which at the time was just as well. But then, if we had heard about it, I am sure, at this stage, it would not have troubled us unduly. Tomorrow was always another day.

A few weeks ago none of us had even heard of DD tanks. But we knew all about them now. Fully trained on them we were, once again, ready for combat. And for some, notably the battle-uninitiated among us – inspired perhaps by the part the Regiment had played in the Battle of the Admin Box – combat, as they often would tell the rest of us, could not come soon enough.

But, wherever that fighting was to take place, the first stage in our getting there was to be some three hundred miles south – the port of Madras, to which soon we would be making our way. Very soon.

During our time in Cocanada – in training for what was now obviously to be a large-scale amphibious assault on some strongly-held, but as yet to be disclosed, Japanese territory – the war in Burma raged on.

With the Regiment, complete with its tanks, now in Madras, no time was wasted to put us in the picture. We were to take part in an invasion of a Japanese stronghold on the west coast of Malaya, code named Operation Zipper.

Initially, B Squadron was to head a large sea-borne landing between Port Swettenham (now Port Kelang) and Port Dickson. After successfully establishing a beachhead, our squadron’s specific objective was a nearby Japanese Officers’ training establishment. Overall, there was, in this region, a formidable enemy strength of an estimated 25,000 men.

After achieving this objective, and then capturing Port Swettenham, we were then to advance south to liberate Singapore, with Port Swettenham as our operational base. The overall operation was code named MAILFIST.

But first our tanks were to be loaded onto LSTs at Madras and then taken into the Straits of Malacca, over 1,700 miles away, to a position just off the stretch of coast that we were to invade. Once in that position our tanks would leave their LSTs and make their own way to the shore.
I was now the 75mm loader/co-driver in the Squadron Leader’s tank, which meant that it would be, if it ever made it that far, the first tank to hit the beach.

Unlike the Arakan campaign when we moved gradually into the war zone with, at first, only limited exchanges of gun-fire with periods of quiet in between – until we were besieged, when everything then changed dramatically – this time we were to go in with all guns blazing right from the start, and were to keep going until our object was achieved. And this time, unlike the Arakan campaign, we were all made fully aware regarding where and what that objective was.

We all now knew the plan and, I suppose, accepted the part we were to play in it as philosophically as our previous experience would allow. Despite the odds being against us when we were besieged in the Admin Box, we had beaten them. So whatever the odds against us this time round, why should we not beat them again? Which might have been for the Box veterans among us, a thought. But if it was, it was, I am sure, only a fleeting one. And I never heard it discussed.

With our new draft – with ideas, perhaps, of emulating our previous victory, but without any idea of the terrifying experience that we endured achieving it – a more confident and excited attitude seemingly prevailed.

But, despite their losses in the Pacific, the Japanese were still resisting fiercely – fanatically so, as demonstrated by their kamikaze attacks on the advancing American battleships. They always resisted that way, so while we knew what to expect, the new draft had yet to discover what that resistance really meant.

With our tanks now aboard the LSTs in Madras harbour, we began loading essential supplies and equipment, one most important item of which had to be our Davis-type escape apparatus. But of all the supplies and equipment that we loaded, there was one item I can remember more clearly than any other. It was a case of evaporated milk the contents for which I had a great liking and to which I looked forward to sampling as soon as the opportunity presented itself. It may seem strange that I should remember so trivial a thought so clearly when so much of greater moment was going on at the time. I cannot explain it.

However, having loaded everything on board, we were now ready to go. And with everything elsewhere now in place, orders were given that we were to sail at 6 o’clock the next morning.

With nothing now to be done before we sailed, we found ourselves at a loose end. Some of us played cards, others decided to write home. I had not mentioned anything to my mother in my previous letters that would cause her any concern or distress, and did not want to do so now. And my father, between his spells of shore leave and sailings, did his bit to reassure her when my letters were not forthcoming by trying to convince her that I was always ‘somewhere behind the lines, mending tanks’ – even though he also had no idea where I was. ‘But I knew you where you were – I knew’, so my mother informed me when I eventually returned home. But for his peace of mind, she let my father think she believed what he said.

I do not recall anyone actually expressing any fear of what lay ahead of us; it could for all intents and purposes have been another training exercise. But then fear in combat, so I found from my experiences in Burma, comes only when the hardware starts flying around. In any case, it would be days before anything like that happened, for we had a long sea voyage ahead of us – and that was something I was looking forward to.

Then, before we could get our heads down for the night, something entirely unexpected and unbelievable happened. A wireless signal had been received. And the whole operation was dramatically called off.

It was the 6th of August 1945. An American B-29 bomber had dropped an atomic bomb on Hiroshima.

Due to sail in just a few hours and keyed up as we were, we found it all so difficult to grasp. But in the light of the morning, when it had sunk in, we were ordered to get our tanks off the LSTs and to assemble in the harbour.

With such a powerful weapon now in Allied hands, for which the Japanese had no answer, the talk among us was that the war for the Japanese had to be over. And for us too.

Three days later, on the 9th August, the Americans dropped a second atomic bomb, this time on Nagasaki … and with the same horrific results.

There was no doubt now that the war was over. It had to be.

And it was. On the 14th August, the Japanese surrendered unconditionally to the Allies.

I cannot recall there being any great celebration at that time. But I did feel, as I am sure most of us did, a great sense of relief. And a feeling of bemusement as we tried to come to terms with this rapid about turn in our prospects. The military authorities were somewhat bemused too, for they could not, it appeared, make up their minds what now to do with us. And while they pondered this, we made the best of things and relaxed in Madras. I do not think that any of us at that time had any idea of the enormity of that atomic onslaught – or of its horrific aftermath.

To fill in the time we would occasionally take the tanks for a run on the roads around the harbour. On one of these runs, on a not too busy a road a couple of days later, I pulled out to overtake a slowly moving bullock cart, whose driver, his head nodding in unison with the gentle to-ing and fro-ing of his cart, oblivious to the world, was fast asleep. As I drew alongside it and let go my left stick to straighten up, the tank, to my horror, began to slide slowly down the camber of the road, sideways towards the cart. And I could do nothing to control it; any action I took would have made matters worse. To pull on my right stick would have resulted in the rear of the tank swinging in to give the bullock cart a knock which, to say the least, would certainly have awakened the driver if not to deposit him unceremoniously on the road. So I just held my breath and prayed as the tank continued its slide, on course to make matchwood of the cart and possible mincemeat of the bullock pulling it. Then, with just a whisker to go, the tank mercifully stopped its slide and righted itself. With a deep sigh of relief, I continued on my way – without so much as frightening the bullock or awakening the driver who was still ‘in control’ of it.

And so, with these excursions and other time-filling activities, we happily passed the time of day. Life was good and we relaxed into it. With our tanks definitely not now required for any further operation, the Regiment moved from Madras to an established base camp where, after a spell, we were granted leave.

Adapted extract from: TELL THEM OF US: The Forgotten Army – Burma by John Leyin
Used with permission

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Message 1 - Secret Training on DD Swimming Tanks

Posted on: 05 October 2005 by S W JACKSON

Ex Stg S W Jackson
Attatched to 25th Dragoons
No 7 Training Team on DD Tanks

I would like to hear from John Leyin
on the subject of DD Tank Training at Cocanada India in 1945.

S W Jackson

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