The Duplex Drive Tanks of Omaha Beach (a) Limited Means and Makeshift Solutions
In the introductory post to this Omaha Beach Series, I stated that Operation OVERLORD’s planning had begun as an under-resourced concept, an error later exacerbated by the necessary — but belated — expansion of the size of the landing force from three to five divisions. The available resources had been inadequate for the three division concept as it was planned, and the expansion of the assault force would strain shipping almost to the breaking point. Indeed, the frantic efforts to find the necessary additional resources had a trickle-down impact throughout planning for Operation NEPTUNE[1] and in many cases at least partially hobbled the attacking forces.
It only seems appropriate that this, the first of these deep-dive explorations, should focus on the first wave to land on Omaha Beach. This wave would include the sixteen Landing Craft, Tanks (LCTs) that were to carry in 64 duplex-drive tanks (DD tanks). For those unfamiliar with such equipment, LCTs were flat bottomed barges, sometimes called tank lighters, designed to land vehicles and personnel on a beach. There were several models, but the LCT(6) version — the type used in this first wave — was about 120 feel long, was crewed by one officer and eleven sailors, could carry as many as four M4 Sherman tanks, were slow (8 knots when empty) and handled open seas rather poorly. Yet they were absolutely essential for a successful amphibious landing. The DD tanks were a modification of standard M4 Sherman tanks that gave them limited ‘swimming’ capability for use in assault landings. Essentially, the tanks were fitted with canvas screens or curtains which would create something like a bathtub configuration that would displace enough water to make the tanks float. For propulsion the tanks were fitted with two propellers in addition to their tracks, hence the term duplex drive. It was a fragile system and fit only for relatively calm seas. As it would turn out, such would not be the case with the seas off Omaha Beach on 6 June 1944.
The plan was that the tanks would be launched from LCTs about 6000 yards offshore and swim into the beach, landing at five minutes prior to H-Hour (H-5 minutes). Two companies of DD tanks (a total of 32 tanks) would land on the eastern half of Omaha beach to support the 16th Regimental Combat Team (16th RCT). Their eight LCTs belonged to Assault Group O-1. Eight LCTs belonging to Assault Group O-2 would bring in two more companies with an additional 32 tank on the western half of Omaha Beach to support the 116th RCT’s landings.
The two groups of LCTs – and their DD tanks – fared much differently. Twenty-nine DD tanks of O-1 were launched between 6,000 and 2500 yards from the beach; 27 sank and only two successfully swam ashore. Three others were delivered directly to the beach. In the O-2 group, the decision was made to bring the DD-tanks all the way into the beach and not have them swim in. The loss of so many DD tank of the O-1 group was something of a disaster. Although no formal inquiry was conducted, soon enough explanations were put forward and scapegoats identified. The crux of the matter focused on two points: the state of the seas, and exactly who made the decisions to launch. The explanations were pretty much a one-sided affair as the key Army officers involved were soon killed in action or their units were rather more consumed with surviving in the ongoing high-intensity combat, than squabbling about past failures. The Navy, on the other hand, left a complete record of its view of how events transpired, and that one-sided perspective has dominated the historical narrative.
It is the challenge of this discussion to examine the plans, the decisions and dispositions which led to the fate of the DD tanks on Omaha Beach, and attempt to arrive at perhaps a more balanced perspective. But first, it is necessary to understand the LCTs involved and their crews.
The Landing Craft Problem
It’s a truism that big navies love big ships and largely ignore small ships. That isn’t as shortsighted as it may first seem. Big ships cost a lot, have long construction times and require major dockyard facilities. So, it isn’t unreasonable that big ships dominate peacetime construction programs. Smaller ships cost less, can be built much more quickly and in smaller shipyards, so naturally in times of peace there is a tendency to defer their construction, reasoning that they can be quickly built when needed, or . . . their roles filled by rapid conversion of civilian hulls.
And so it was that the US approached December 1941 with a fairly good doctrinal foundation for amphibious warfare,[2] but a nearly bare cupboard of necessary assault ships and craft. The swelling pre-war naval construction programs in 1939-41 virtually ignored the smaller classes of ships, especially the specialized landing ships and craft. In fact, several of the designs that would prove essential to victory originated in Britain, where they had been forced to come to grips with the challenges of amphibious warfare before the US had even entered the war. The US Navy really only began to fully face up to the problem as plans were being formulated for the invasion of North Africa (Operation TORCH). The shortfall of assault craft was so severe that the President had to direct a crash ‘tiger team’ effort to rush construction of enough craft to support the landings. And that effort ended up disrupting almost every major ship construction program to one degree or another. The ‘reasonable’ pre-war focus on major ship construction no longer seemed so reasonable.
This crash program did succeed in producing enough craft to make TORCH possible, but the new level of sustained production was mostly swallowed up by continuing operations in the Pacific and the Mediterranean. There was only a relatively small amount left over to accumulate a modest reserve in the UK to support an eventual invasion of the continent. But then another long-standing crisis demanded attention.
At the start of 1943, the continuing success of the German U-boat campaign made it clear this threat had to be defeated if the Allies were to win the war. At the Casablanca Conference in January 1943, the Combined Chiefs of Staff declared, “The defeat of the U-boat must remain a first charge on the resources of the United Nations,” which then drove priorities on construction.[3] Accordingly, the President refocused the “tiger team” on production of destroyer escorts. The priority assigned to assault shipping and craft was so low that they were not even mentioned in his production plan for 1943. Despite three major conferences which directed concentration of assets in the UK for the invasion of the Continent, assault hulls simultaneously remained a critical shortage and a low priority for construction. Even when the US Navy finally agreed to increase LCT production in the Fall of 1943, it was felt the additional craft could not reach the UK in time for the invasion, so NEPTUNE would have to make do with the already scheduled rate of allocations.
And that directly led to the shortfall of hundreds of LCTs and other craft that Lieutenant General Frederick Morgan faced (as discussed in the preceding installment). One hundred and fifty-six LCTs would eventually be needed for the Omaha Beach landings, but as of 1 September 1943, not one of them was at hand. Ninety-three of these LCTs hadn’t even been built, and in many cases their crews had not yet even been inducted into the Navy or Coast Guard. A further 27 would be obtained in a circuitous manner. They originally had been delivered to the Royal Navy through the Lend-lease Program. Although hard-used and in poor materiel condition, the decision was made to refit them for various specialized roles and then ‘reverse Lend-lease’ them back to the US Navy, to be manned by green crews. The transfer would occur none too soon.
The only veteran LCTs would be the 36 craft from Flotilla 18, which had been put in service between August and November 1942 and had served in the Mediterranean. The problem with this flotilla was that they originally had been allocated to Operation ANVIL, the plan to invade the south of France simultaneously with the Normandy landings. It was not until late March 1944 that Eisenhower finally had to admit the two invasions could not be supported and cancelled ANVIL.[4] LCT Flotilla 18, and other assault vessels, were moved to the UK where they were able to participate in the final round of invasion rehearsals.
What of the LCTs allotted to the DD tank landings? These would all be new construction with equally new crews. The following chart lists the LCTs and the date they were accepted from the shipyards.
This is a somewhat bizarre allocation of craft. Considering this would be the very first wave of the landings — carrying in the 64 DD tanks upon which the infantry and engineers would rely so heavily for fire support — not a single veteran craft or crew would be assigned to the task.[5] The naval commander for Force O (the amphibious force conducting the landings at Omaha Beach) was Rear Admiral (RADM) John R. Hall, Jr. As we’ll discuss in later installments, placing the newest craft with greenest crews in the lead waves for the most critical roles was something of a theme in Hall’s planning for NEPTUNE. The two tank battalions embarked in these LCTs were at least two years in service and well trained. Placing their fate in the hands of greenest LCT crews was a gamble.[6]
The good news about the selection of these LCTs was that they all came from just two flotillas — excepting just two from a third flotilla — which should have aided cohesion. The bad news was that the flotillas were just as new as their craft and crews, so there was little in the way of organizational cohesion to fall back on. The matter of command effectiveness was complicated by the fact that the leader of the ill-fated LCTs of the O-1 group was from Flotilla 19, while six of the eight LCTs in his group were from Flotilla 26. This did little for continuity of command and would be further complicated when he was directed to switch to another craft in his group late in the game.
When considering the dates these LCT were accepted by the Navy from the yards, it would be easy to conclude that the majority of the crews would have six months or more to gain experience with their craft and in operating within their flotillas before D-Day. But that is misleading.
The dates listed above are when the LCTs were accepted from the builders’ construction yards. They then had to be shipped or sailed to the port of departure for the UK. Some LCTs would move as completed craft on the decks of the larger Landing Ships, Tanks (LSTs); these could be partially outfitted in the US before being hoisted aboard their LST. But the number of LSTs allocated for Europe was limited, so most of the LCTs could not be assembled when loaded on typical cargo ships. That wasn’t a major problem. LCTs were constructed in three sections specifically for ease of movement on Liberty ships; they could then be bolted back together once they arrived overseas. And this is how most of the new construction LCTs arrived in the UK. The new craft would arrive at a departure port in the US, be broken back down into three sections and loaded as deck cargo on a Liberty ship. This consumed a bit more time, but economized on shipping, which, with the continuing U-Boat losses, was the primary constraint. The wait for available shipping and the period in convoy across the Atlantic consumed more time. Once arriving in the UK, the LCTs had to be reassembled, which was done either in a British shipyard, or by a newly assigned crew. The crews had been trained in the Chesapeake Bay, shipped separately overseas and often only first saw their new craft on arrival in the UK.
After assembly came outfitting and a brief shakedown cruise, if they were lucky. From there it was back to the yards to correct any materiel deficiencies, and then mandatory time in a shipyard to make six important modifications required for operations in the ETO. These included everything from longitudinal stiffening of the hull, modifications of the ramp and addition of radios.[7] Assuming all this went as planned, the crews took over and sailed for whichever port was home to their new flotilla. In many cases, this trip was their first experience on the open ocean. To give you an idea of how green the crews were, one craft left the Themes estuary and mistaken crossed the English Channel and sailed into German-occupied Boulogne, where they were promptly captured.[8]
All of the foregoing consumed months, leaving little time for the new crews and craft to absorb their new duties and the skills needed for working within their flotillas. Speaking of the final full scale rehearsal for the Omaha Landings (Exercise FABIUS I, 3-6 May 1944) RADM Hall noted in his report:
“Unfortunately, due to the late arrival of the landing craft in the Theater, plus the necessity of alterations and repairs to put those already present in the best possible condition for the assault, only between sixty and seventy percent of the landing craft which eventually took part in the assault under Force “O” took part in this exercise.”[9]
As we’ll see, the 16 DD LCTs destined for Omaha Beach had a little luck in that regard.
The DD Tank School
As with so much of the D-Day preparations, the DD tank effort was a last minute, rushed affair. Because there were no DD versions of the M4 Sherman in the UK, limited training was conducted from the middle of January to the middle of February 1944 on the British DD version of the Valentine tank. Major (MAJ) William Duncan, executive officer of the 743rd Tank Battalion, had attended that training with a few men from his unit and was selected to establish a DD tank training school. The school would train two tank companies from each of three tank battalions. The 741st and 743rd Tank Battalions were tagged for Omaha Beach, and the 70th Tank Battalion for Utah Beach. Meanwhile, the Navy’s Lt. Dean Rockwell, commander of Group 35 of Flotilla 12, was charged with providing the landing craft to support MAJ Duncan’s training, as well as training the LCTs for their role in the invasion. The school was set up at Torcross, adjacent to the Slapton Sands training area, with the LCTs based out of the nearby city of Dartmouth.
COL Severne MacLaughlin, (commander of the 3rd Armored Group, to which the 741st and 743rd Tank Battalion belonged) provided an outline for training in a 27 February memo, which initially focused only on his two battalions. The tank companies would arrive without tanks; their DD tanks would be issued at the school as they arrived from the States. MacLaughlin hoped the training could be conducted from 20 March to 4 April assuming the tanks had arrived by then. The training would last five days for each of his two battalions. However, the first 15 DD tanks were not scheduled to arrive until about 15 March, and ten of them were to go to the British. After arrival, the tanks required several modifications (to include “modifications accomplished to struts to avoid sinking vehicles”!), so the initial five tanks might be available for the start of training on 20 March, with the next shipment of 24 DD tanks due to arrive from the states by the start of April.[10]
[Images by Dr. Dan Saranga via The-Blueprints.com]
Launching DD tanks was a delicate and tricky operation, with far more ways it could go wrong than right. The canvas flotation screens could be easily snagged and ripped by fixtures in the LCT during loading. And to avoid damaging the tanks’ propellers, the LCT had to be backing at 1,600 rpm while the tanks actually drove off the ramp. When the tanks left the ramp, they initially dropped down into the water until the screens provided enough buoyancy to halt the downward travel and lift them them in the water to the point of stability. The problem was, at the point the tanks left the ramp, they were only partially immersed, and the initial downward plunge from that height was so deep that the sea could overflow the canvas screens, resulting in a sinking tank. In an attempt to fix this, special ramp extensions were hurriedly developed that would support the tanks until they were deeper into the water, so the initial plunge would not be so bad. These modifications delayed how soon the selected LCTs could be available to support training.
As a result of these delays for both Army and Navy equipment, initial training would get off to a slow start, necessitating a longer training plan.
By the end of April, formal training had concluded and on 1 May, Duncan and Rockwell submitted reports to their respective superiors. The reports were obviously tightly coordinated and the two officers were in agreement on all significant points. Rockwell reported he had trained 23 of the 24 LCTs required to land all three battalions’ DD tanks, and urged they be dedicated to the mission for the invasion. He also claimed 1,087 tank launchings from LCTs with only two tanks lost and no personnel casualties. Duncan’s report noted that 250 DD tanks had been received and prepared, with 100 used in training. His training results included over 1,200 launches from LCTs, 500 launches from land and 800 hours of water navigation. He also reported six cases of carbon monoxide poisoning (nonfatal), three tanks lost and three killed.[11]
Of the several comments and recommendations the two made in common, three would turn out to be significant: 1) the DD tanks should be launched no more than 4000 yards from the beach; 2) the decision to launch should be made by the senior Army officer, and 3) the DD tanks be limited to a Force 3 wind and sea.
There is some conflict in the records whether DD tanks were employed in either of the two major rehearsals for Utah and Omaha Beach, due to the security concerns over these top secret tanks. In fact, on 25 March, MG Heubner (commanding the 1st Infantry Division) recommended that the DD tanks not be waterborne for the upcoming rehearsal and instead should operate from their training site at Torcross.[12] On the other hand, Rockwell’s report specifically mentioned 31 DD tanks launching as part of Exercise TIGER (the Utah Beach rehearsal). It is believed the 1st Division’s DD tanks did participate in Exercise FABIUS I (the Omaha Beach rehearsal) but I have not located a source to verify that.
After formal school ended, the DD tanks continued training of one sort or another in preparation of the invasion, including sight alignment and check firing of their new guns. Rockwell continued training LCTs, including the last of his 24 primary craft (LCT 713). In addition, he trained several backup LCTs. As the plans worked out, all of the initial 23 LCTs he trained (and the late arriving 713) were kept together for the D-Day mission.
The entire effort was a last minute and hurried affair, beset by late arriving tanks, a crash training schedule and green Navy crews. But the men who had been made responsible for getting it done had performed their best to make it work. The question was, would that best be good enough?
But Why Bother With DD Tanks?
Given the late and chaotic nature of the DD effort, it is fair to ask, why was it even necessary? And to answer that, we need to address the not so minor issue of bombardment.
Unlike some Pacific islands, where naval bombardment could stretch for days without fear that the isolated defenders could be reinforced, in Normandy every minute after discovery of the invasion fleet could be used to rush enemy reserves to the threatened beaches. Hence, landings on the Continent needed to be scheduled to touch down as soon after dawn as other considerations would permit. For D-Day, those other considerations included preparatory air bombardment, naval bombardment and the tide. This allowed only about 40 minutes for preparatory air and naval bombardment, ceasing at about H-Hour when naval firing would shift to inland targets. That wasn’t much time. In theory, if your allotted bombardment time was short, you should compensate by increasing the number of barrels firing. But Neptune was working on a shoestring here, too. Between Utah and Omaha Beaches, only 3 old battle ships, 1 monitor, 8 cruisers and 20 destroyers were allotted.[13] By comparison, the invasion of Saipan was scheduled just one week later. Its bombardment force included seven new fast battleships, seven old battleships, 11 cruisers and 23 destroyers firing over multiple days. Having gained momentum in what would prove to be a long series of amphibious assaults in the Pacific, the US wasn’t especially keen to divert ships and lose that momentum just for the sake of a 40 minute bombardment in what might well be the last amphibious assault in the ETO.
So, the Western Naval Task Force was faced with too brief a bombardment window and far too few barrels. Several measures were taken to try to fill this gap. A number of LCTs were converted to carry 1,064 rockets of 5 inch diameter, and nine of these were allotted to Omaha Beach. It was intended they would fire their rockets just before the first wave landed. In addition, 24 small Landing Craft, Support (Small) (LCS(S)) were each equipped with 24 rockets, which they would fire as they escorted the first waves into the beach. And additional LCTs would be loaded with Army self-propelled howitzers, which would provide artillery support afloat. These were good efforts to fill the bombardment gap, but these craft were not stable platforms, and they lacked sophisticated gunnery controls that might ensure accuracy.
That then left the option of fire support ashore. Having tanks ashore early is always a good idea, as any infantryman can tell you. In the case of the Omaha landings, this need was greater due to the limited sea-based bombardment. Normally, one battalion of tanks would support a division (of three regiments), but for Omaha Beach there would be a tank battalion supporting each assault regiment. The trick was, how to get them ashore. There were only enough up-armored LCTs (termed LCT(A)s) to land one company from each battalion directly on the beach (along with one tank dozer in each LCT(A)), and even these were pressed into the fire support role. Elevated platforms were built at the front of these craft to enable the forward two tanks to fire over the bow ramp during the ride into the beach. As early as December 1943, the Army was casting about for more makeshift solutions, even considering light tanks for the first wave. But these were only armed with 37mm guns, which were deemed inadequate. A month later, the DD tank concept was being seriously considered (which spurred MAJ Duncan’s attendance at the training that month). Not only would DD tanks avoid having to run unarmored LCTs into the beach in the first wave, but it was hoped the unexpected sight of them crawling out of the sea would have a demoralizing effect on the defenders.
And so it was the late and hurried DD tank effort was yet another result of launching NEPTUNE on resources that were barely adequate. No one was entirely happy with this hodge-podge approach. As RADM Hall put it:
“The Force Commander [talking of himself in the third person] acquiesced reluctantly in both the decision to employ tanks and artillery firing from landing craft, and to land tanks in the first wave. He ultimately agreed because he realized the necessity for more firepower at this stage of the assault than could be supplied by the Naval craft then available. He was then, and still is, doubtful of the efficacy of DD tanks and tanks firing from LCT(A)s landing in the first wave on strongly defended beaches.” [14]
In light of these constraints, the Allied naval commands took pains to point out that the effects of the bombardment were likely to be limited. Although the bombardment was expected to have a “neutralizing” effect, they wanted it clearly understood that in this case, “neutralizing” meant a stunning effect, not a destructive one. The Army had similarly cautioned that the “drenching fire” mission of its wave 1 and 2 tanks was intended to stun and suppress, not necessarily destroy. Perhaps the cumulative effect might be greater when combined with the attack by the heavy bombers of the US Army Air Force, but no one at the higher levels harbored any delusion about the expected results. Unfortunately, many of the assault troops would later report they had been incorrectly assured the German defenses would be destroyed.
As the shortcomings in planning and early errors in execution began to plie up, success of the landings in turn hung more heavily on the success of the DD tanks.
[1] A note about codewords. OVERLORD and NEPTUNE were closely interrelated and often used interchangeably. OVERLORD was the umbrella plan for the assault on the continent and defeat of Germany. NEPTUNE was the codename for the plan for the amphibious assault on the Atlantic coast of France. In this installment, the focus of discussion centers on the amphibious landings, and therefore examines the NEPTUNE plans.
[2] At least theoretically. It would take several actual landings by Army and Marine divisions to hone the theoretical doctrine into a practical system.
[3] Memorandum by the Combined Chiefs of Staff, “Conduct of the War in 1943”, 19 January 1943.
[4] Renamed Operation DRAGOON and rescheduled, these landings took place on 15 August, using some of the assault shipping that had been employed in NEPTUNE.
[5] The 16 LCTs carrying in the wading tanks and tanks dozer scheduled to land just minutes later were in even worse condition. Originally given to the UK under the Lend Lease program, these LCT had been modified with additional armor and returned to the US for various fire support roles. All of these were delivered to US units during the first half of 1944, necessitating the formation of scratch crews which had either no or minimal training on the craft.
[6] Hall was an experienced amphibious commander, having commanded an assault force in the Sicily invasion (Operation HUSKY), and before that had been Admiral Hewitt’s chief of staff for the North African landings (Operation TORCH). He had been the Eighth Amphibious Force commander in the Mediterranean before he was transferred to become the Eleventh Amphibious Force Commander in the UK. As COM Eleventh PhibForce, he was selected to lead the Omaha landings.
[7] Six major modifications had to be performed on the LCTs for the DD tanks. In additional, all LCT engines had to be overhauled in preparation for the assault. See Report of Commander, Amphibious bases, UK, titled “A History of the United Stated Amphibious Bases in the United Kingdom”. Dated 1 November 1944. Pg. 61.
[8] This anecdote was recorded by Charles Lilly, Jr. in his account of his war service. He was the Officer in Charge of LCT 637 on D-Day. Although LCT 637 was delivered to the Navy on 19 January 1944, it did not join its flotilla until the end of April, missing the major rehearsals, and had just 3 weeks to work up before embarking cargo for the invasion. Fortunately, the 637 was not one of those supporting the DD tanks.
[9] COM 11th PHIBFOR (Hall). Report of Ops Period 6/4-29/44-Assault on Vierville-Colleville Sector, Coast of Normandy, France. Dated 27 July 1944. Pg. 88.
[10] Commander 3rd Armored Group (MacLaughlin). Memo, subj: DD Tank Training, dtd 25 March 1944.
[11] The difference in losses resulted from one non-training accident when an impromptu demonstration was put on for a visitor. The tank swamped.
[12] Commanding General, 1st Infantry Division (Heubner). 1st Endorsement, dtd 25 March 1944, to Commander, 3rd Armored Group memo, subj: DD Tank Training
[13] The monitor (the HMS Erebus) was a flat bottomed ship boasting just a single turret with two 15 inch guns (same as found on some battleships). It was specifically designed for shore bombardment. The total of destroyers includes three British Hunt class escort destroyers.
[14] Op cit, Hall, pg 101.