World War II: RAF Flight Sgt. Jack Nissenthall's Secret Role in Operation Jubilee at Dieppe | HistoryNet MENU

World War II: RAF Flight Sgt. Jack Nissenthall’s Secret Role in Operation Jubilee at Dieppe

6/12/2006 • World War II

On the night of February 27, 1942, British parachutists raided St. Bruneval on France’s northwest coast. They came away with the key parts of a German Würzburg radar set, one of a chain that directed anti-aircraft fire and controlled night fighters intercepting Allied bombers flying to inland targets. The coup enabled the British to develop countermeasures.

Another British attempt to steal German radar secrets was made nearly six months later. Overshadowed by the larger operation of which it was a part, it remains a lesser-known episode in World War II history. The second raid also proved a success, despite the fact that stubborn German resistance prevented the raiders from lifting any of the radar hardware. The target this time was Germany’s basic radar equipment–the Freya early-warning device.

Whereas Würzburg, operating at an ultrashort wavelength, had a range of only 18 1/2 miles, the larger but less precise Freya, using a longer wavelength, had a range of up to 125 miles. It could pick up Allied aircraft almost as soon as they became airborne. Working in tandem, the two radars posed a serious threat to the aerial offensive against Adolf Hitler’s Germany. To make matters worse for the Allies, they learned that the enemy had improved its Freya radar and intended to use it as the primary German radar defense network. This, of course, made the British more anxious than ever to confirm what they had learned and to discover what made Freya tick so that it could be neutralized.

As early as 1941, British listening posts had detected signals emitted by a new, high-powered Freya installed atop a cliff between the seaport of Dieppe and Pourville, two miles farther west. The site was marked as a potential target, one of the most convenient locations for a future raid. The St. Bruneval success made it unlikely that a similar foray against the Freya would succeed, however, since the Germans had significantly beefed up their radar station defenses after the earlier raid.

The opportunity to examine the instrument and remove its innards came with an operation known as Jubilee, a rejuvenated version of an earlier discarded plan. There were a number of reasons for Jubilee, not the least being American and Soviet pressure to open a second front against the Germans, an invasion of Western Europe that would help relieve the hard-pressed Soviets to the east. The immediate overall purpose of Jubilee, according to an official British history, was to ‘test the enemy’s coast defenses and discover what resistance would be met in seizing a port; it also hoped to inflict wastage on the GAF (German Air Force), thereby giving some relief to Russia.’ Even though Allied capabilities precluded a full-scale invasion in 1942–as realistic planners fully recognized–a hit-and-run raid larger than the earlier Commando stabs would prove beneficial for planning the real invasion at some future date.

Jubilee’s target had to be a medium-sized and moderately defended port well within range of air cover. Dieppe was selected. Located only 67 miles from England, the city had hosted the Norman fleet that crossed the English Channel to land near Hastings in 1066. It had been occupied by the Germans once before, during the 1870-71 Franco-Prussian War.

As often happens during military operations, a simple and feasible plan was transmuted into an oversized scheme with proportionately greater risks. The final decision, based on incomplete intelligence, was for a mainly frontal assault on a well-defended gravel and pebble beach without preliminary air bombardment and with minimal naval fire support.

The operation would include Canadian (the main contingent), British, French and American elements. Fifty U.S. Army Rangers who participated in Jubilee would be the first American troops to land in Europe since World War I. Jubilee’s objectives were to destroy enemy installations (including the inland airfield at St. Aubin), capture Germans for interrogation, steal documents, bring back moored enemy invasion barges, release French prisoners, and tackle the Freya site atop its 300-foot-high cliff. The biggest such operation of the war, Jubilee received final approval only a week before it was launched.

As in the St. Bruneval raid, the unit assaulting the Freya site would have to include a radar expert. Twenty-four-year-old Flight Sgt. Jack Maurice Nissenthall of the Royal Air Force (RAF), who had volunteered for’special missions in which my expertise would be of value,’ was chosen for the job. An electronics specialist, Nissenthall was a cockney from London’s East End. His father was a Jewish tailor who had immigrated to Britain from Poland in 1912. Nissenthall had been working on radar since 1937.

Since the radar expert selected for the mission knew British secrets that had to be kept from the Germans, the printed orders received by officers in charge of the Freya assault team stated that the ‘RDF (radio direction finder) expert must under no circumstances fall into enemy hands.’ As a result, 10 riflemen of Company A of the Canadian 2nd Division’s South Saskatchewan Regiment were specifically tasked with providing protection for Nissenthall. If the RAF sergeant was in danger of being captured by the enemy, however, he was to be killed by his own bodyguards.

Operation Jubilee was launched during the breezy night of August 18-19. An invasion force of just over 6,000 men sailed southward from five southeastern British ports aboard 237 vessels, toward Hitler’s ‘Fortress Europe.’ Immediately facing them were about 1,500 soldiers of the Dieppe garrison, the German Fifteenth Army’s 571st Infantry Battalion, which was backed by other units of its parent 302nd Infantry Division, as well as by panzer forces farther inland. Their will and defenses had been strengthened in the wake of a July 9 directive from the Führer warning that ‘it is highly probable that an enemy landing will take place shortly in the area.’ The period from August 10 to 19 was designated by the German high command as ‘invasion possible’ because of favorable moon and tides.

At 3:48 a.m., the Allied armada ran smack into a five-ship enemy convoy. During the ensuing shootout, the convoy’s three small escort vessels battered one British Commando group’s landing craft before being counterattacked by the Polish destroyer Slazak. Two radio warnings from the British Admiralty about the convoy’s approach never reached the Jubilee force commander. Antenna damage prevented the German escort vessels from warning the mainland of the approaching invasion force, but, as it turned out, no warning was necessary.

Just minutes before a star shell triggered a 10-minute naval engagement, the operator in the tiny cabin beneath the cliff top Freya antenna had detected five columns of vessels about 21 miles offshore. He dutifully passed the information on to the men in the concrete-covered brick blockhouse supporting the Freya. Inside the three-room, sandbagged blockhouse sat a range reader and a plotter, connected by landline to the site’s command post and an analysis center located on the other side of Dieppe. Jubilee’s last veil of secrecy had fallen.

The alerted radar section commander reported the ominous radar contact to both army and naval units. The latter pooh-poohed the report, but the army did not. The navy would soon pay for its skepticism when its coastal artillery battery, unlike the army’s, quickly fell to a Commando attack during the battle that followed.

Trailing phosphorescent tails in the cold, choppy waters, the LCA (landing craft, assault) of two Commando groups made a run from their mother ships to beaches east and west of Dieppe. They landed mere minutes before 5 a.m. The Commandos were to silence the heavy artillery batteries flanking the city so that the tank-supported main assault against Dieppe’s narrow streets and cliff-hugging harbor could be made half an hour later.

The South Saskatchewan Regiment’s LCAs churned shoreward on the left flank of the westernmost Commando group. Their objective was the shoreline, designated Green Beach, at Pourville. Inside one of the landing craft was Jack Nissenthall–nicknamed ‘Spook’ by his invasion companions because of his intelligence mission–who was expected to return with a lot of answers to questions about Freya (and hardware to back those answers). Although he, too, wore a helmet and battle dress over an inflatable life vest, Nissenthall was armed only with a revolver. He carried a blue RAF haversack crammed with hand tools.

As the boats neared the beach, the men checked their individual weapons, and a container of rum was passed around. Enemy fire began shortly after the Canadian LCAs thudded onto Green Beach and dropped their front ramps. Company A was to scamper immediately up the western cliff slope to assault the radar site while Company C secured the village. Companies B and D were to move inland to establish a position to block enemy reinforcements. Another Canadian unit, the Queen’s Own Cameron Highlanders, which landed about half an hour later, was to speed inland against the St. Aubin airfield 3 1/2 miles away.

By the time Nissenthall and his group had crunched across the stony beach in the growing light to the protection of a sea wall topped with barbed wire, they realized that the navy had deposited them nearly 500 yards too far to the west. Instead of landing at the base of the Freya cliff on the other side of Pourville, Company A was in front of the German-occupied village. Using scaling ladders, they traversed the 8-foot-high sea wall, crossed a promenade and advanced into Pourville.

There were British planes overhead to provide cover for the Allied troops, but until the Luftwaffe arrived, the support they provided was mostly psychological. Small-arms fire and grenade blasts filled the air with smoke as the invaders fought their way into the town by fits and starts. An obscene trail of still and writhing bodies marked their progress. Following the shoreline through Pourville, Company A soon found the path to its objective blocked by pillboxes at both ends of a bridge crossing the small Scie River. Just beyond, an unpaved lane snaked up to the cliff, while the road turned right to run along the river. On top of the cliff, the Freya antenna methodically pivoted to and fro as it continued to track and report Allied aircraft movements.

If not for the boat handler’s error, the company would have landed on the other side of the bridge and probably already been on the cliff top. Machine-gun fire from the nearest pillbox dropped one Canadian after the other to the pavement. Finally, during a pause, one of the South Saskatchewans sprinted forward to lob two grenades through the firing slit of the pillbox. That did the trick. Led by their battalion and company commanders, the Canadians cleared the bridge and began to ascend the grassy height under fire from above and the right. Nissenthall and his bodyguards followed the advance, running between a stone church and a hotel to cross the body-littered bridge.

Shell bursts and small-arms fire followed the zigzagging soldiers up the mostly open slope. There now were only about 24 men left of Company A’s original 100. Nissenthall’s bodyguards were down to seven, three of whom were lightly wounded. The RAF sergeant later recalled being temporarily deafened when ‘one of the men carrying a backpack of mortar shells was hit and blown to pieces by his own shells’ only 20 feet away. Tossing smoke canisters and seeking what little cover they could find on the way up, the remaining men finally reached a point just below the top, where they stopped.

To the left was a sheer white cliff, with rocks and shingle below. Straight ahead, just to the left of the pebbly lane, lay the coveted Freya. It was protected by barbed wire, riflemen in slit trenches and machine-gun nests. Lying in a narrow, hedge-lined depression slightly downhill from the radar site, the company commander turned to Nissenthall and said: ‘Well, there it is. Take it if you want it.’

The radar antenna’s motions–limited to a 180-degree horizontal arc and pausing as it focused on individual targets–were revealing. They told Nissenthall that the Freya was a target-discriminating precision instrument and that it was connected to the operator’s cabin and blockhouse by coaxial cable–unlike British radar, which could turn through a full circle by using rotating electromagnetic coupling.

More detailed information could not be obtained by simple visual observation. Company A obviously was in no shape to attempt an assault to get closer, however. Clearly, help was needed, but the company’s radio was out of commission. After a brief discussion, Nissenthall and two of his bodyguards raced back to Pourville, which was now under steady fire from Germans on the high ground to both sides of the town. At battalion headquarters, the three men learned that shore-to-ship communication was virtually nonexistent.

Unable to enlist shipborne guns to soften up the Freya site as they had hoped, they gathered together a small mortar team. That effort was brutally aborted by a well-placed enemy shell. An unhurt but frustrated Nissenthall once more ran the gantlet of fire to rejoin Company A.

Less than two miles on the other side of the Freya cliff, the main invasion force, despite some initial successes, had bogged down and was being beaten back. The smoke of battle rose into a clear blue sky where dueling fighters fought for supremacy, raining empty shell casings over the countryside. From almost every direction came the thump of cannons and the chatter of small arms.

In desperation, Nissenthall made a second escorted return to Pourville to seek reinforcements. This time he returned with a mortar crew, which, while providing additional firepower, didn’t get the men any closer to their goal. The sergeant then decided to implement a suggestion made before his departure from England. If the Freya’s landlines to its command post and analysis center were severed, the radar crew would have to use radio to relay its information on Allied air movements. This radioed information could then be monitored to provide the British with a fairly accurate idea of the radar’s performance.

Nissenthall could see the critical telephone cables silhouetted against the sky about 120 feet away at the crest of the hill. On all fours, the sergeant left cover and started through the tall grass. He moved past a half-hidden machine-gun nest, the ground vibrating against his body from the weapon’s persistent chatter. Nissenthall made it undetected to a triple-pole cable support just outside the Freya perimeter, whose defenses were aimed to the front and sides but not the rear.

Nissenthall removed and pocketed two wire clippers from his haversack, and as he subsequently reported, ‘I wedged myself between the poles and worked my way to the top.’ There, 15 feet above the ground, he cut the Freya’s six outside communications wires. He quickly rejoined his companions, who apparently had been in no condition to weigh Nissenthall’s odds of evading death or capture.

Still hoping for a chance to take a closer look at the Freya, a haggard and sweating Nissenthall returned to Pourville for the third time. His intent was to commandeer a tank and batter his way into the radar site. (Original Jubilee planning, which had proved to be overly optimistic, had called for some of the Churchill tanks that landed at Dieppe to move inland toward Pourville and escort the raiders back to the seaport for evacuation after their mission was completed.)

This time, the Company A commander sent all seven remaining bodyguards to escort his’spook.’ After more than four hours of battle, Pourville was a shambles. The outgoing tide was exposing more bodies and discarded materiel. Nissenthall persuaded a number of Cameron Highlanders still in the village to accompany his small group as it set off to the southeast along a blacktop road on which the tanks were expected to arrive.

Reaching the village of Petit-Appeville about a mile away, the soldiers stopped at its crossroads to rest and wait. Before long, they heard the characteristic rumble and clank of approaching armor. The armor soon appeared–not British, but German tanks accompanied by bicycle troops. Nissenthall and the Canadians fled in panic as the enemy opened fire. Many fell en route back to Pourville, including another three of the sergeant’s bodyguards.

The Canadians in Pourville were at a last-stand stage while landing craft, slow-moving targets for German guns on the heights, did what they could to recover survivors. As casualties mounted and the defense perimeter shrank, Nissenthall, as yet unhurt, could not help but wonder what his chances were of staying alive. His escorts remained under orders to kill him if capture seemed imminent. If that was not enough, he also had to consider the cyanide pill he had been given as a last resort.

The escort destroyer HMS Brocklesby moved toward the beach, laying down a smoke screen to protect the milling LCAs. The warship’s 4-inch guns blazed at one major source of German fire, and a section of nearby chalk cliff blew apart. An eerie silence followed as other enemy guns stopped firing so as not to attract the ship’s attention. The beleaguered Canadians cheered, and a number of them took advantage of the lull to sprint across 200 yards of open ground to the sea, in hopes of being rescued. Nissenthall and his bodyguards joined them.

The Germans opened fire anew from nearby houses, the high ground and the sea wall over which the Canadians had leaped. Discarding their helmets and gear as they ran past the wounded placed beneath the sea wall, the men splashed into the water. The sergeant and his one remaining bodyguard, miraculously unhit by the hail of lead, dived beneath the surface and swam underwater as long as they could. Lungs bursting, they surfaced and continued seaward toward the landing craft popping in and out of the dark smoke screen. Their partly inflated Mae Wests enabled them to pause occasionally to rest until they were picked up by an LCA. Shell bursts pursued the boat into the smoke, then ceased.

As the boat emerged from the billowing murk, it was set upon by two enemy fighters. This was, to Nissenthall, ‘the most frightening episode of the whole raid.’ German 20mm cannon shells slammed against the small craft’s sides, and it began to take on water. The battered LCA slowly sank, even as its exhausted occupants were being hauled aboard an escort destroyer.

With the destroyer bringing up the rear, a variety of smaller vessels churned northward, away from the French coast. German air attacks continued as the battered flotilla crossed the Channel, overwhelming the outnumbered British Supermarine Spitfires and Hawker Hurricanes.

Operation Jubilee was a costly disaster. Numerous factors, including inadequate supporting fire and a delay in landing the tanks, had doomed it from the start. A withdrawal under fire began at 11 a.m. that fateful Wednesday and continued for about three hours. More than 3,600 men in the invading force were killed, wounded or taken prisoner. The Royal Navy incurred another 550 casualties and lost a destroyer and 33 landing craft. The RAF lost 106 aircraft to the Luftwaffe‘s 48. German ground losses were only 591. Whether or not ‘the successful landing in Normandy (on June 6, 1944) was won on the beaches of Dieppe,’ as Combined Operations Command Chief Lord Louis Mountbatten stated, important lessons were learned from the mission and applied to future operations.

Nissenthall disembarked at Newhaven late that August 19. The next morning–in his own words, ‘dirty, dishevelled and unshaven’–he rode a commuter train to London. There, he reported to the Air Ministry building for a full debriefing. If the sergeant was disappointed that he had not been able to examine the Freya firsthand and return with its innards, he was pleased to hear that his severing the telephone lines had provided the Allies with priceless information. British eavesdroppers, listening to the temporarily open German radio plotting that directed Luftwaffe interceptors, learned much about both enemy aircraft control methods and the performance of the key Freya radar. One result was the creation of suitable jamming equipment, a task assigned to Nissenthall.

Nissenthall was unable to tell his story for 25 years because of the Official Secrets Act. His next assignment was in the Middle East, where he set up a defensive radar system. After the war he married, shortened his name to Nissen and moved to South Africa.

Years after the war’s end, the Company A commander, who had been captured at Pourville, got together with Nissen. As they reminisced, the former captain told Nissen that he had found the order he had received regarding his’spook’ so repulsive that he had put it out of his mind for 20 years and then wondered if it all had been a figment of his imagination. ‘Could you have shot me?’ asked Nissen. The answer was, ‘Yes, probably I would have.’ Nissen knew too much about Allied radar.

This article was written by Wil Deac and was originally published in the February 1998 issue of World War II.

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