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DD Tanks for D Day – Operation Overlord

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“DD Tank” doesn’t stand for D–Day Tank. These two letter Ds are the acronym for Duplex Drive. They have been the “amphibious” Sherman tanks meant to offer armored help to the Operation Overlord landings on all 5 seashores. Their use was a bitterly debated part of the invasion plans, for a lot of reasons. Not least amongst them was all the concept of the Normandy operation, which ran counter to amphibious warfare doctrine developed with years of bloody expertise within the Pacific theater. The impression of the “swim tank” on the Allied try and safe a lodgement assorted wildly from beachhead to beachhead. Learn on to study extra. Read on.


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Swim Tanks: Floating Armor

The Doubtful Deployment of Duplex-Drive Tanks at Normandy

The necessities of struggle typically result in ingenious innovations out of sheer want. Some work out; some don’t. A type of innovations in the Second World Warfare was the Duplex-Drive (DD) Tank. The DD Tank rose from the perceived want for an amphibious tank to swim ashore to help the preliminary waves of an amphibious touchdown.

The thought wasn’t anything new. The US army had tested an amphibious tank as early as 1924 when work was just beginning on what would turn into American amphibious doctrine as practiced in WWII. It shortly turned clear that troops needed direct hearth help towards enemy emplacements as they landed on a hostile seashore. Calls for a tank able to swimming ashore with the troops continued throughout the 1930s but funding was never out there, and no workable designs got here to the fore.

US forces in the Pacific overcame the shortage of a real amphibious tank by arming amphibious tractors (LVT or AMTRAC) which ferried many troops ashore. Relying on the configuration, the LVTs carried .30 and .50 caliber machine weapons, 37mm cannons, and 75mm howitzers in turrets situated forward of the cargo area. M4 Sherman tanks have been introduced ashore in devoted tank touchdown craft referred to as LCTs (Landing Craft, Tank) and have been fitted with particular prolonged exhaust ports and waterproofing so they might wade via shallow water (see my article, Island Hopping With Tanks).

Backing up the LVTs and Shermans have been the guns of the US Navy, which not solely saturated the target area with indirect bombardment, however with accurate direct hearth utilizing armor-piercing shells from battleships, cruisers, and destroyers. The Navy had labored out their primary hearth help doctrine in the 1930s and perfected it by late 1943 in the landings within the Marshall Islands. By the point of the assaults on Kwajalein and Eniwetok, the Navy/Marine Corps staff, and Army models following Navy/Marine doctrine had turn out to be an amphibious warfare machine. They wanted no stinking tanks that would swim.

But LVTs were not obtainable in Europe for the Normandy landings. Allied planners knew they wanted something to fill the direct hearth position, plus they felt that the presence of tanks on the seashore would increase troop morale while hurting that of the defending Germans. Which will have been true, contemplating that two of the three US divisions (the 4th and 29th Infantry Divisions) within the first wave can be receiving their baptism of fireside at Normandy. Solely the veteran 1st ID had seen fight before. Whether or not the defenders would have been affected is questionable at greatest. The German 352nd ID at OMAHA Seashore was a top-quality unit with in depth combat experience. The US 4th ID landed towards comparatively mild opposition at UTAH Seashore.

The DD Tank

There isn’t a denying the DD Tank concept was an revolutionary, if flawed and misused, response to the need for direct hearth help. The technical flaws usually are not troublesome to elucidate. Simply put, the DD Tanks have been M4 Shermans with hooked up propellers and a water-proof canvas curtain that allowed them to drift. The tank commander steered by a gyroscopic direction-finder and a periscope. The curtain could possibly be lowered in just some seconds as soon as the treads hit the sand, clearing the gun for fight. That’s principally it.

Duplex Drive Sherman Tank

The tanks might float, although they have been far from secure, they usually might make about 4 knots in calm seas, and therein lies the first drawback. In testing off the coast of England, the tanks have been blessed with calm water, they usually carried out as promised. But the English Channel on the morning of 6 June 1944 was something but calm. The previous couple of days had been stormy, causing Basic Eisenhower to postpone the landings once, from 5 June to six June. Allied meteorologists detected a short break within the climate for 6 June, and Ike rolled the dice moderately than postpone once more. Nevertheless it was windy and overcast, with waves within the three to four-foot vary with some as high as to six ft. The DD Tank’s curtain was not designed for that type of a beating, and the Army knew it. The DD Tanks’ coaching workouts have been all the time canceled in dangerous climate or something aside from optimum circumstances.

The second drawback was with the engine exhaust. Testing had proven that there was an actual danger of carbon monoxide poisoning to the crew because the fuel from the exhaust had hassle rising out of the excessive curtain. The maximum vary for the tanks to function earlier than posing a dire asphyxiation danger to the crew was 4,000 yards (about 2.3 miles). The Military and Navy have been each aware of the restrictions of the DD Tank. Officers from both providers advisable that DD Tank models be guided by experienced navigators and that the choice to launch be made by an Military officer accustomed to the capabilities and limitations of the tanks and their crews. The Army and Navy command structure ignored these suggestions.

The choice to launch was made by the DD unit commanders and the help flotilla commanders themselves, lots of whom felt they need to press ahead with their obligation as they saw it. However because of the worry of German artillery, the LCTs have been presupposed to strategy no closer than 6,000 yards (about 3.5 miles) off OMAHA. Because of the tanks’ sluggish velocity within the water, they needed to be launched forward of the infantry so they might land at the similar time. The infantry needed to experience 11 miles in their touchdown craft in rough seas. So, the commanders had to determine. Many selected to go, possible with various misgivings.

OMAHA Seashore – the worst waters

A lot of the DD Tanks designated for the japanese half of OMAHA Seashore, in help of the 16th Regimental Combat Workforce of the 1st ID, sank. Lots of their curtains collapsed as soon as they hit the water, causing them to sink immediately. Others went down more slowly, however still close by of their LCT. Some managed to stay afloat and struck out for the seashore. Several tanks launched despite the fact that they might clearly see the automobiles in front of them disappearing beneath the waves of the English Channel. We will only speculate that they felt it was their obligation to take action, or maybe they thought they might make it. Of the 32 tanks of Corporations C and D of the 741st Tank Battalion, 26 sank. Of the remaining six, solely two made it ashore beneath their own power. The remaining have been landed immediately onto the seashore by their LCT, whose ramp had malfunctioned, stopping it from launching at sea. A lot of the tanks sank as a result of being swamped in the heavy seas, although it is attainable that exhaust fumes overcame a few of the crew through the trip to the seashore.

The 743rd Tank Battalion, assigned to the western half of OMAHA in help of the 116th RCT of the 29th ID, fared higher because of the help flotilla commander’s quick recognition of what was occurring when the first couple of tanks from the 741st sank. It’s no coincidence that this man, Lieutenant Dean L. Rockwell, had been the officer who really helpful warning to the Navy on the deployment of the DD Tank. He and the battalion commander shortly agreed to take the tanks to the seashore on the LCTs.
The DD Tanks met with combined outcomes elsewhere. The circumstances at UTAH have been much less severe than at OMAHA, and extra tanks made it ashore and carried out nicely. It possible helped that the DDs have been launched just one,000 yards (solely about .6 miles) off UTAH. There have been comparable outcomes on the British seashores. Some have been lost, however not on the size as at OMAHA. Some historians have claimed it was the employment by the American crews that was at fault. That’s potential, contemplating the launch distance, but the British DDs off SWORD Seashore have been launched at 5,000 yards (2.9 miles) and 31 of the 34 made it ashore. Almost certainly, it was the circumstances themselves mixed with unproven know-how, because the seas and currents off OMAHA have been extra extreme than the opposite beaches. Their presence on the opposite seashores little question contributed to the success of the landings.

DD Sherman launching from an LCTDD (Duplex Drive) Sherman tank launching from an LCT.

V Corps commander, Basic Leonard T. Gerow, wasn’t a fan of the DD Tank and argued towards its use however was overruled by First Army commander Common Omar Bradley and Eisenhower, who both appreciated the concept. After the struggle, Gerow admitted that extra DD Tanks made it ashore than he would have ever believed. However their absence on Omaha was keenly felt.

The poor efficiency of the DD Tank at OMAHA was partially the result of an incoherent amphibious doctrine in the European Theater. As an amphibious warfare historian, I consider there ought to never have been a perceived need for something just like the DD Tank. I don’t need to get too deep within the weeds, however I’ll clarify what I mean. By 1944, US forces in the Pacific had honed their amphibious doctrine to a positive edge. The Navy/Marine/Military group was so good at getting ashore that the Japanese stopped bothering to defend the seashores after the Marianas fell. The ship-to-shore motion, logistical procedures, and hearth help methods have been all however perfected. Solely minor changes needed to be utilized to satisfy the wants of particular person operations. In fact, the Navy and Marines had been engaged on that stuff since 1921. The Military models in the Central Pacific fell beneath Navy management when it comes to finishing up the landings, in order that they benefited from that physique of data although the Military had never put a lot effort into amphibious know-how.

ETO vs PTO Doctrine

Pacific Theater classes vs European Theater misconceptions

The state of affairs in Europe was just the other. Regardless that the US Navy possessed one of the best amphibious doctrine on the planet, the Military referred to as the photographs. And the Military thought they knew better, regardless of having the providers of Vice Admiral Kent Hewitt, one of many Navy’s prime two practitioners of amphibious warfare (the opposite being Admiral Kelly Turner within the Pacific).

To be truthful, the Army in Europe had a unique mission than the Marine and Army models within the Central Pacific. The latter have been specialized assault troops, particularly the Marines. Getting ashore towards heavily defended beaches was what they did, and brother, by mid-1944 they did it damned nicely. But the Military in Europe couldn’t afford to have a specialized drive like that. Their infantry models’ main function was to prosecute a continental land marketing campaign towards the German Army. The divisions that landed in the first waves at Normandy acquired amphibious coaching, but that they had other things to fret about too. The problem wasn’t in the troops themselves, but in the help they acquired.

Navy/Marine Corps doctrine employed large amounts of naval gunfire in the form of preparatory bombardments and direct hearth help towards enemy emplacements. The Navy’s massive guns would typically pound the Japanese for every week before the infantry set out for the seashores. That they had devoted hearth help ships which have been stocked with high explosive shells for antipersonnel missions and armor piercing rounds to use towards enemy bunkers and pillboxes. HE rounds have been additionally fired on the seashore itself to explode enemy mines and destroy obstacles and wire.

Navy and Marine pilots have been additionally highly expert in the art of shut air help. Marine close air help pilots had to be qualified squaddies before they might fill that position. The Navy and Marines placed qualified pilots with the bottom troops as spotters to talk to the pilots. Plane pounded the Japanese for days, and even weeks, earlier than the landings and then operated with the infantry on the bottom. One of many key parts of the Pacific doctrine was the last-minute airstrike towards the beaches simply earlier than the primary wave of the landing. The beaches have been plastered for several minutes to keep the enemy’s head down proper because the touchdown craft have been coming in. The whole process was devastating. That’s what prompted the Japanese on Iwo Jima and Okinawa to fortify additional back from the seashore and only contest with artillery. They knew they couldn’t stop the infantry from getting ashore, and if the infantry might get ashore, so might the armor. All this was accomplished in daylight to maximise the effectiveness of naval and air help.

Issues have been totally different in Europe. Although naval gunfire had carried out admirably within the North African, Sicily, and Salerno landings, the Army nonetheless believed it was not suitable to help daylight landings. Which was one purpose the Military decided to land at night time in all three of these operations. The opposite foremost purpose was to realize tactical surprise, which they did in North Africa, about halfway in Sicily, and by no means at Salerno. It had been the Navy’s huge guns that have been principally liable for breaking apart the assault of the Hermann Gӧring Panzer Division towards the Sicilian beachhead and that of the 16th and 29th Panzer Divisions at Salerno. The state of affairs at Salerno was especially dire and could very properly have pushed US forces off the beaches.


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Navy air help was not obtainable in Europe either. Pilots from the service Ranger offered excellent help for Patton’s touchdown in Morocco and ol’ George begged for his or her help at Sicily, nevertheless it was not forthcoming because of the assertion that land-based Army aircraft had it coated. The problem was that Army pilots had little to no coaching in close air help. Once more, the air forces in Europe had totally different priorities, like air superiority and bomber escort missions. But the Navy discovered it attainable in the Pacific to execute air superiority and escort missions while additionally offering close air help. It was more a matter of the Military putting a very low precedence on such missions than anything.

Hewitt tried to convey Eisenhower and Bradley around to the Navy way of thinking, but they have been having none of it. They even blew off Main Common Pete Corlett, who was one of the Army’s prime amphibious guys within the Pacific. Corlett had commanded the seventh ID at Kwajalein and had been sent to advise Eisenhower and Bradley for OVERLORD. Corlett was shocked that neither man needed to hear what he needed to say. They informed him that Pacific operations have been “bush league” and that European ops represented “graduate-level” amphibious warfare. Army command believed that the Normandy operation was distinctive in historical past and required distinctive solutions. It actually wasn’t unique besides when it comes to complexity, however the primary amphibious doctrine was nothing new. They only made it more durable than it needed to be. A basic case of not seeing the forest for the timber. The command disregarded Corlett’s experience but gave him command of XIX Corps, which wasn’t activated till every week after the landings.

A British Sherman tank (DD) Royal Hussars pushing in from the beach.A British Sherman tank (DD) Royal Hussars pushing in from the seashore.

D Day

The results of all this was that crucial Allied (American and British) operation of the conflict was carried out with less than half of the naval gunfire help used in attacks towards a single island within the Central Pacific and the one air help was a pre-landing strike by the B-17s of the Eighth Airforce. The DD Tanks have been thought-about essential as a result of landing them in LCTs would take away from the even dispersion of armored belongings and risked their being destroyed or damaged in bunches if their LCT was targeted because it landed. They have been also deemed essential as a result of the Army had no faith in naval gunfire. Planners tried to offer extra hearth help in the best way of touchdown craft armed with guns and rockets. They might be effective in optimal circumstances, however the chop off OMAHA Seashore made it almost inconceivable to goal the rockets, which have been presupposed to detonate the minefields. They failed to take action.

The story of OMAHA Seashore has been advised time and again. I gained’t repeat it right here. Suffice to say that the large airstrike by the B-17s didn’t go so properly. The airmen insisted that the bombers are available perpendicular to the seashore as an alternative of parallel, for which Navy doctrine referred to as. The perpendicular avenue of strategy meant the release needed to be absolutely good for the bombs to hit the target. Wellll…it wasn’t. The bombers flew at high altitude, and the overcast was at 2,000 ft. The pilots feared dropping the bombs brief and hitting friendlies, in order that they overcompensated and dropped them nicely behind the seashore. This was a bit of an issue since these bombs have been supposed to help blow up the mines on the seashore and assist tear up some obstacles as well as demolish German emplacements. So that was a no-go. We’ve already seen how the DD Tanks have been additionally a no-go.

Finally, the plan only allowed for a 25-minute preparatory bombardment to melt enemy defenses whereas Navy UDT teams and Army Engineers had the same period of time to clear sixteen lanes via the obstacles for the landing craft. Right here is the place the supposedly “unique” character of Normandy reared its head. Touchdown in darkness on a falling tide was not ultimate, nevertheless it had been achieved, and it’s virtually certain the troops would have landed rather more easily. There would have been little help from the Navy till the sun came up, however they wouldn’t have had to cross 400 yards of open seashore in full view of the bluffs overlooking OMAHA Seashore after landing in daylight at low tide. Landing in darkness would have lowered the demands on the demolition groups because the dangers of bunching up the landing drive beneath hearth would not have been as acute. Landing at night time was a viable choice.

DD tank with lowered curtain“Swim tank”? A DD tank with lowered curtain. Most Duplex Drive tanks have been Shermans, but there were British Valentine versions as properly.

An alternative choice would have been to land in daylight on a rising tide with the complete drive of the Navy behind the landings by way of an extended preparatory bombardment and, once once more, more time for the demolition teams. Planners felt that a longer bombardment would sacrifice tactical surprise, giving the Germans time to react. This purpose rings hollow given the injury achieved by the air drive to the French transportation system in the earlier months, in addition to the fact that Allied minesweepers had been operating in sight of the seashores the earlier night. Not to mention the 23,000 or so paratroopers who had been sowing confusion behind the seashores all night time.
So, as an alternative of going with what had worked, albeit imperfectly, within the Mediterranean, or what was even then working within the Pacific, Allied planners went for the in-between. The outcome was stop-gap measures like the DD Tank to make up for the shortened hearth help from the Navy. Because it turned out, the Navy and the resilience of the US infantryman needed to carry the day at OMAHA. US Navy destroyers closed to 500-800 yard to pour direct hearth on German emplacements. Several models on the seashore truly directed destroyer hearth with hand alerts, and a couple made radio contact. The battleship Texas hammered the Vierville exit with near-direct hearth from its 12-inch weapons, proving instrumental in opening a main path off the seashore.

Squaddies for the 1st and 29th IDs started infiltrating between the German robust points on the seashore exits when the plan had been to attack from the entrance with armored help. The robust factors have been ultimately taken from the rear as US troopers fanned out on the bluffs. Even so, it was a near-run factor. It was avoidable. The DD Tanks, as an idea, performed no very important position, as they have been too few in number and had too far to undergo still-intact obstacles underneath enemy hearth. They might have been simpler had they been landed from their LCTs underneath a proper naval hearth help plan, as within the Pacific, or even landed at night time.

In an ideal world, Marines would have been out there to assault the beaches supported by the Navy, with Army maneuver models set to cross by way of and increase the beachhead. But these Navy and Marine belongings have been somewhat busy on the other aspect of the globe. The Military had to go together with what that they had. However that doesn’t mean they essentially did it right. In the long run, it was the lads themselves who improvised, tailored, and overcame (sorry, I couldn’t resist that one, nevertheless it’s true). As we already know, the credit for eventual success on OMAHA belongs to them.

Duplex Drive Sherman tank with curtain raised Duplex Drive Sherman tank with raised curtain. The DD.Tank won’t have been the strangest of all WW2 tanks, but when not it’s definitely a contender.

Surprisingly, a lot of the 135 males who took a swim within the Channel when their tanks went down survived. The Army had outfitted them with life vests and rafts, as well as an adaptation of what was referred to as the Davis Lung. Thirty-three males drowned. Twenty-five have been recovered over the subsequent couple of days. An effort was mounted immediately after the warfare to recuperate the opposite eight bodies, however none have been discovered. Another expedition was sent in 1987 after divers reported seeing remains in the hulk of a DD Tank on the underside. Nothing was discovered. No further efforts have been forthcoming, and the sunken tanks stay in their watery graves.

Gordon Harrison, Cross-Channel Attack
Adrian R. Lewis, Omaha Seashore, A Flawed Victory
Williamson Murray and Allan R. Millett, A Warfare to Be Gained, Preventing the Second World Struggle
William F. Lawson, The Army Means; American Joint Operations in Europe in World Warfare II, A
Doctrinal Analysis Master’s Thesis, American Army University


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