“We sailed along in fatal ignorance,” writes Lieutenant Eugene E. Eckstam, a medical officer aboard the first of two tank landing ships to be sunk by German S-boats off the southern coast of England on the night of 27/28 April 1944. The attack, which happened in the midst of an Allied dress rehearsal for the Normandy landings, killed hundreds of men. Some of them succumbed to blast injuries and burns, others to drowning or hypothermia.
The disaster that befell Convoy T-4 was not a fluke. It was the product of an effort by the Germans to disrupt preparations for the invasion of northwestern France, and it happened as a result of actionable intelligence from the Luftwaffe and Germany’s B-Dienst. Tank landing ships (LSTs)—slow, unwieldy, and cavernous—were ideal targets for fast torpedo boats, which patrolled those areas that the German admiralty determined most likely to host enemy convoys and training exercises. With only one escort and no meaningful radio capabilities, Convoy T-4 stood little chance.
Exercise Tiger was supposed to ready Force U for landing at Utah Beach, in Normandy, in spring 1944. Rear Admiral Don P. Moon headed the force, which by 27 April counted 221 vessels in and around Lyme Bay on the south coast of England.
Because the exercise had to provide Force U with the realistic experience of combat, it included all the equipment, fully loaded, that the men would later bring onto Utah Beach. Cruisers and destroyers would exchange live fire over the heads of the trainees as they landed at Slapton Sands, the rehearsal location on the English side of the Channel, with the very same vessels Force U would use on D-Day.
Allied Supreme Headquarters finalized plans on 19 April 1944 and established U.S. Navy control over the exercise, but Royal Navy Admiral Ralph Leatham retained, in his words, “overriding control, should there arise circumstances which render it strategically necessary for me to cancel or curtail the exercise.” It then fell to Rear Admiral John E. Wilkes, USN, to ensure the servicemen’s readiness for this realistic and therefore dangerous exercise, for which the Royal Navy contributed destroyers, corvettes, and trawlers as escorts and covers.
The men of convoy T-4—including the 4th Infantry Division’s combat-ready engineers—were afforded only two escorts. The Royal Navy’s other possible escorts had their work cut out for them elsewhere on the Channel and in the Atlantic, where the German navy redoubled its efforts in anticipation of an Allied invasion.
In November 1943, Hitler had issued Directive No. 51, which adopted Colonel General Alfred Jodl’s recommendation for a “strategic pivot” from the eastern front to the west, where a decisive blow against Allied forces in the event of an invasion might decide the outcome of the war in Germany’s favor. Grand Admiral Karl Dönitz, Germany’s highest-ranking naval officer, saw clearly that the strategic pivot relied disproportionately on the German navy, since “the Luftwaffe hardly gets off the ground anymore.” On 10 April 1944 (less than two weeks before Exercise Tiger), Dönitz called on “every serviceman of the navy to take risks without consideration for the survival of the ship itself.” In this suicide pact, German sailors relied heavily on S-boats for their agility and speed.
As Royal Navy Captain Stephen Wentworth Roskill notes in his history of the British war at sea, the Allies’ “chief troubles” in the Channel and other coastal waters “arose from German E-boats,” the Allies’ moniker for S-boats (short for the German word Schnellboote, meaning “fast boats.”) Roskill goes on to explain that the S-boats, “though never more than about three dozen in number, could be switched rapidly from one convoy to another; and, by choosing their own moment to attack, they occasionally brought of some unpleasant successes.”
Under such dangerous circumstances, therefore, the U.S. and Royal navies insisted on radio silence during Exercise Tiger, except in cases of imminent danger (when, in the event, it would prove too late for action).
Before leaving their ports, the LSTs’ crews made sure that the trucks, tanks, and other vehicles were replete with fuel, a further nod to the exercise’s aspirations to realism. Eckstam, then a medical officer, remembers the process of loading LST-507 and getting underway on 24 April 1944. At sea, his and the other two LSTs from Brixham joined five more LSTs from Plymouth, and Convoy T-4 was born. In three days’ time, the men expected to land at Slapton Sands as a follow-up convoy to the previous day’s landings. In the meantime, they were to progress slowly toward Lyme Bay and attract as little attention as possible.
Unfortunately, however, the Germans were watching and listening. Hitler’s Directive No. 51 had focused much of what was left of the German navy onto the English Channel and near Atlantic. The Luftwaffe sent reconnaissance planes to the area on 25 April just as preparations for Exercise Tiger were coming to an end and the LSTs of Convoy T-4 were reaching Lyme Bay.
What German reconnaissance saw was the military buildup in Exercise Tiger’s staging area—the harbors and inlets around Portsmouth. At Spithead roadstead, the Germans counted more than 200 trucks. In and around Southampton, they observed ships, including destroyers; troop transporters; and a great many LSTs and land vehicles. At Portsmouth Harbour, the Germans sighted cruisers, destroyers, and smaller vessels and vehicles. At Pagham, Chichester, Langstone, and Exbury harbors, as well as in the mouth of the river Hamble, the Germans spied still more landing vessels. German intelligence services were also listening to the radio, which confirmed some of what they saw.
German intelligence officers reckoned that several tens of thousands of men might be carried and protected by this flotilla on England’s south coast. Far from perfect and always subject to Allied deception, German intelligence was nonetheless broadly correct on this occasion. None of what they saw was the product of Allied deception but rather the product of reality: the staging of Exercise Tiger, set to begin in fewer than two days.
The Germans continued to observe and to listen, and on 26 April, the eve of the exercise, German intelligence reported to the admiralty that the enemy’s “concentration in the Channel is confirmed anew.” Confident of their assessments, German observers and analysts were now providing actionable intelligence to the admiralty in Berlin.
Convoy T-4 in Lyme Bay
Convoy T-4 got off to a bad start. The second of only two escorts, HMS Scimitar, could not join at the last minute, her hull having been rammed by an American landing craft for tanks (LCT). Convoy T-4 now had to make do with just the one escort, HMS Azalea, under the command of Lieutenant Commander George C. Geddes of the Royal Navy. The convoy itself, however, was the charge of Commander Bernard Skahill, USN, embarked on LST-515. Both he and his British counterpart on Azalea had been briefed about the dangers from German S-boats. Armed with guns and torpedoes, these vessels were some of the fastest available and demanded constant vigilance and responsive action. Both would be harder to effect now that Convoy T-4 had only one escort.
In the middle of the night, British radar spotted S-boats in the vicinity of Convoy T-4. So did the crew of one of the LSTs. They chose not to act, however, under the assumption that these mystery vessels belonged to another Allied convoy. British coastal gunners also sighted the S-boats and alerted Azalea but took no further action because they were under orders to hold their fire. Azalea, for its part, took no action.
And then, shortly after 0130, men on several of the LSTs caught sight of green tracers and heard approaching gunfire. Lieutenant j.g. James Murdock and the bridge crew of LST-507, soon to be under attack, sounded general quarters, but it was too late.
Murdock and his crew in the bridge then observed two approaching craft. These were S-130 and S-150, both of which were closing on LST-507.
Suddenly, the sound of grinding issued from deep within the ship, according to Petty Officer Third Class Bill Gould. S-130 and S-150 were already firing torpedoes, but none had yet managed to detonate until S-130 achieved a direct hit: the auxiliary engine room, which exploded and cut the lights for the entire ship.
“I was stupidly trying to go topside to see what was going on,” Eckstam remembers, “and suddenly ‘BOOM!’ There was a horrendous noise accompanied by the sound of crunching metal and dust everywhere. The lights went out and I was thrust violently in the air.”
The auxiliary engine room fire quickly spread to the parking deck, where trucks, tanks, jeeps, and landing vehicles sat with full tanks of gas. There were mobile guns and ordnance, too. “We watched the most spectacular fireworks,” Eckstam notes of the final moments on deck. He had just come from the fires, where he was trying to see if anyone could be rescued. “The screams and cries of those many Army troops in there still haunt me,” he remembers. Fast, hot air from the “raging inferno” then pushed him back to the tank deck’s hatches, which he subsequently dogged per Navy regulations.
“We sat and burned,” Eckstam explains, with “gas cans and ammunition exploding and the enormous fire blazing only a few yards away.” Less than a half hour after the torpedo hit, it was time to abandon ship.
The Soldiers had not received training for how to abandon a fast-sinking inferno. Some of them were still wearing their full packs when they jumped overboard. Heavy steel helmets and improperly fastened lifebelts also hastened drowning.
As LST-507 burned, radio operators aboard the other LSTs sent queries but received no reply. (The LSTs were stretched out over several miles at this point.) And so, in radio silence once again, the rest of the convoy continued in line. For now, they were oblivious to the emergency.
Suddenly, at 0217, another LST—531—erupted in flames as a result of two torpedo hits. Reports indicate that she continued to return fire as she sank in under 10 minutes. Reports also indicate that 467 of LST-531’s 496 men died as a result of the sinking or the explosion.
By now, the remaining six ships of Convoy T-4 were zigzagging wildly as deck crews fired machine guns and cannon into the darkness. LST-289 took aim at one of the S-boats but could not escape damage. S-145 fired a torpedo that smashed the rudder and stern guns as well as the crew’s quarters. Still afloat, LST-289 eventually made it to shore. The other vessels also made way for the relative safety of shallower depths.
And now, in the oil-slicked, debris-strewn water, only 42 degrees, men formed concentric rings around floating objects as a means of staying above the surface.
LST-515, with Commander Skahill embarked, returned to the scene some two hours later. According to historian James Foster Tent, the reason was a disagreement over whether the S-boats were still prowling the waters. They were not.
Upon arrival back at the scene, the crew of LST-515 found hundreds of bodies—intact and otherwise—amid living men in the throes of hypothermia. “I was a brand new Naval Reserve medical officer,” Eckstam explains, “fresh out of an abbreviated senior year and internship, totally unprepared for what was to follow.” Moreover, the warm baths, compresses, and other treatments for people about to freeze to death were unavailable.
Historians are unclear on the number of victims, in the end, but all agree that the death toll approached or exceeded 700, more than would die in the actual landings at Utah Beach some five weeks later.
The decision to give T-4 only two escorts was probably made under pressure: The Royal Navy had few escorts to spare. The decision to proceed with only one escort, however, is harder to explain. It exposed the men of Convoy T-4 to a level of danger that they would not have to face even on D-Day.
As historian Nigel Lewis has noted, the mixed-command and -responsibility structure also proved dangerous. Still, the command structure in this respect gave both the Americans and the British the right to call off the exercise or some part of it. Remarkable yet unexplained is the failure to do so when Convoy T-4 lost one of its two escorts.
The mixed-command and -responsibility structure also produced catastrophic failures of organization and communication. Scimitar, the other escort for T-4, should have been replaced after having been damaged at Portsmouth. Apparently, a replacement vessel was on hand, but a miscommunication resulted in it staying at port. Even more troubling, the sailing orders for T-4 left out the instruction that the LSTs change to a certain frequency at a certain time. By the time of the attack, therefore, the LSTs (American) were tuned in to a different frequency from that of their escort (British) and of personnel at U.K. shore installations, who did indeed sight the S-boats in advance of the disaster. When Commander Geddes of Azalea received their warning, however, he assumed that the LSTs had received it as well and were making preparations. Yet those LSTs would have heard nothing of note, as they were on the wrong frequency.
The abundance of caution around radio communication (the effort at radio silence, the mid-exercise change in frequency), incomplete instructions, and endemic faults of organization all combined to undermine the risk mitigation already in place. Caution around radio communication did produce the radio silence to which planners aspired. But because the radio silence was involuntary — produced by confusion about frequencies — rather than voluntary, and therefore permanent rather than situational, radio silence failed to save the men of Convoy T-4. And it was radio silence, in part, that also caused their demise.
These failures of communication and risk mitigation were easier to fix than the underlying problem, however: Just weeks from D-Day, the Allies now knew they had failed to secure the approach to Normandy. The S-boats had gotten away.
Six Weeks Later
But after the disaster, Allied commanders and their advisors recognized the unique vulnerability of LSTs to S-boat attack and planned accordingly. They eventually landed on the decision to eliminate Germany’s S-boat force in the Channel. General Dwight D. Eisenhower’s staff at the Supreme Headquarters of the Allied Expeditionary Force organized a sea and air war against the S-boats, which finally bore fruit on 14 June 1944.
Royal Air Force Lancaster bombers equipped with 12,000-pound “tallboy” bombs eliminated, as if in one fell swoop, the Germans’ ability to wage S-boat warfare in the Channel. The bulk of the force had been at port in Le Havre, where at least a dozen S-boats now lay beyond repair. Six more had fallen prey to RAF attacks elsewhere.
The war diary of the German admiralty made the rare recommendation that someone inform Hitler in person of the catastrophic strike. Now the enemy’s LSTs, with the vital equipment and personnel they carried, would be able to cross the Channel unimpeded by S-boats, Germany’s last-ditch effort to frustrate the liberation of Western Europe.
—Adam Bisno, PhD, NHHC Communication and Outreach Division, April 2019
 James Foster Tent, E-Boat Alert: Defending the Normandy Invasion Fleet (Annapolis: Naval Institute Press, 1996), 12.
 United States Naval Administration in World War II: United States Naval Forces, Europe–Histories, vol. 5: The Invasion of Normandy: Operation Neptune (1948), 365, accessed here on 11 April 2019.
 Ralph Leatham, memo of 1 January 1944, quoted in Nigel Lewis, Exercise Tiger: The Dramatic True Story of a Hidden Tragedy of World War II (New York: Prentice Hall, 1990), 45.
 Tent, E-Boat Alert, 12.
 Michael Salewski, Die deutsche Seekriegsleitung, 1935–1945, vol. 2: 1942–1945 (Munich: Bernard & Graefe, 1975), 406–11 and 414–16.
 S. W. Roskill, The War at Sea, 1939–1945, vol. 3: The Offensive (London: Her Majesty’s Stationery Office, 1960), 1:284.
 Tent, E-boat Alert, 13.
 Eugene E. Eckstam, “The Tragedy of Exercise Tiger,” Navy Medicine 85, no. 3 (May-June 1994), 6. A shortened version of this article can be found here.
 Werner Rahn and Gerhard Schreiber, eds., Kriegstagebuch der Seekriegsleitung, 1939–1944, part A, vol. 56: April 1944 (Berlin: E. S. Mittler, 1995), 546–7, entry of 25 April 1944; hereafter: KTB Seekriegsleitung.
 Jak P. Mallmann Showell, German Naval Code Breakers (Annapolis: Naval Instititute Press, 2003), 129, who notes that German estimates of Allied build-up might have skewed higher as a result of radio deception. Cf. Salewski, Seekriegsleitung, 416. On the Allied responses to their security having been compromised, see R. A. Ratcliff, Delusions of Intelligence: Enigma, Ultra, and the End of Secure Ciphers (Cambridge: Cambridge University Press, 2006), 162ff.
 KTB Seekriegsleitung, 566–7, entry of 25 April 1944.
 Ibid., 567, entry of 26 April 1944.
 Lawrence Paterson, Schnellboote: A Complete Operational History (Barnsley: Seaforth, 2015), 281.
 Tent, E-boat Alert, 14–15.
 Marinegruppenkommando West, Kriegstagebuch 16.–30.IV.44, entry of 27 April 1944, in Record Group 38, German Naval Records, National Archives, College Park. See also Paterson, Schnellboote, 2015.
 Tent, E-boat Alert, 15.
 Eckstam, “Tragedy,” 6; Tent, E-boat Alert, 20.
 Ibid., 18.
 Paterson, Schnellboote, 281. According to Paterson, LST-511 was also hit at this time but by duds.
 Tent, E-boat Alert, 18.
 Ibid. Paterson, Schnellboote, 281–2; Morison, Naval Operations, 66.
 Tent, E-boat Alert, 13.
 Ibid., 20.
 Marinegruppenkommando West, Kriegstagebuch 16.–30.IV.44, entry of 27 April 1944, in Record Group 38, German Naval Records, National Archives, College Park.
 Tent, E-boat Alert, 5.
 See Gordon A. Harrison, United States Army in World War II: The European Theater of Operations—Cross-Channel Attack (Washington, DC: Center for Military History, 2002), 270; Morison, Naval Operations, 66; Tent, E-boat Alert, 20; Martin K. Gordon, “Wharton, James E.,” in The D-Day Encyclopedia (op. cit.), 596; Grove, “Amphibious Assault,” 49; Brooks E. Kleber, “Utah Beach,” in The D-Day Encyclopedia (op. cit.), 44; Charles B. MacDonald, “Slapton Sands: The Cover-up That Never Was,” extracted from Army 38, no. 6 (June 1988), 64–67; Malcom Muir, “Moon, Don P.,” in The D-Day Encyclopedia (op. cit.), 373; Paterson, Schnellboote, 282.
 Lewis, Exercise Tiger, 45.
 Tent, E-boat Alert, 14.
 In fact, the Germans had been losing S-boats at high rates since the start of 1944, according to historian Lawrence Paterson, Schnellboote, 280.
 KTB Seekriegsleitung, 420, entry of 15/16 June 1944.