Kapitänleutnant Günter Poser ordered U-202 to dive. It was the morning of 1 June 1943 and he had been located by British warships using high-frequency direction-finding equipment (known as ‘Huff-Duff’). Poser was relaxed; he had been attacked five times on this patrol.


Six British sloops deployed, speeding 20 miles to the location. The only trace of the enemy, when they arrived, was a barely detectable swirl of water. Little did Poser realise that he had attracted the attention of Captain Frederic ‘Johnnie’ Walker, the scourge of the U-boats.

Poser and his men heard the ominous ping ping of sound waves echoing off their craft. They were sent from a British invention called Asdic (better known as sonar) which determined the range and location of submerged objects. Up in Walker’s ships, Asdic operators read the deep by listening to the pings. Down in the U-boat, Poser also studied the pulses, which gave away the presence of the enemy.

Walker sent three sloops to patrol in case there was another U-boat lurking ready to torpedo distracted British warships. The black flag was raised on Walker’s sloop, HMS Starling, the signal for attack. Starling steamed in to drop depth charges. This was a moment of opportunity for Poser. Asdic searched ahead of a ship, while depth charges were launched from the stern (at the rear). This meant that the attacking ship lost contact with its prey in the final seconds, allowing U-boat commanders to take evasive action.

In swooped Starling and launched her depth charges in a pattern. The sea frothed and plumes of water were thrown skyward.

Poser was more than equal to this challenge. He twisted U-202 out of the way of the exploding charges, altering course sharply, knowing that the Asdic echoes would be disrupted by the churning water. Walker lost the U-boat. But no other officer in the Royal Navy had studied U-boats as intensely as Johnnie Walker. He had with him some of the best submarine hunters in the service, men whom he had trained. A young midshipman recalled a quiet man who had a “tremendous presence through his sheer commitment, professionalism and devotion to the task…One knew he was in total control, with a sure grasp of tactics, strategy and the minutiae of the operation. Everyone knew what was expected of them – and dreaded letting him down by not doing it.”

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The strain of the Battle of the Atlantic was etched on Walker’s face. He was a tall, gaunt man who looked older than his 48 years. He joined the navy as a cadet in 1908, during which time he was marked out as a future star, and served throughout the First World War. After the Armistice he developed a passion for anti-submarine warfare.

But the service had little need of his talents. Throughout the interwar years the navy believed that the threat from enemy submarines was minimal. Anti-submarine specialists were sidelined; Walker’s career entered the doldrums. At the outbreak of the Second World War he was an aging and poorly regarded officer, relegated to staff work.

On the defensive

Meanwhile German wolf-packs devastated British shipping. “The Battle of the Atlantic was the dominating factor all through the war,” wrote Winston Churchill. “Never for one moment could we forget that everything happening elsewhere, on land, at sea or in the air depended ultimately on its outcome.” Between June and October 1940, 270 Allied ships were sunk. The Royal Navy’s convoy escorts stuck to defensive tactics.

The caution was still evident at the end of 1941 when Walker finally returned to sea. He was charged with protecting a convoy bound from Gibraltar. During this epic voyage the convoy was attacked by wolf-packs. But rather than just defend the merchantmen, Walker took his faster ships in pursuit of the enemy. It was a risky departure from convention.

By the time the convoy reached Liverpool it had lost two merchant ships, a destroyer and an improvised aircraft carrier. But five U-boats had been sunk during the battle. It was the first major victory for the Allies in the Battle of the Atlantic. Walker’s aggression shocked the German U-boat service, which regarded itself as invincible.

Johnnie Walker advocated ‘offensive lunges’ by British warships, which should not cling to the fringes of convoys but target enemy submarines as far away as 30 miles. Walker had one priority: to hit the enemy as hard, quickly and relentlessly as possible, forcing them to dive so that they could be destroyed underwater. The Admiralty was not ready for innovation. Walker was called back to desk duty. Meanwhile the numbers of U-boats rocketed and Allied losses mounted. In March 1943 alone, 120 ships were sunk.

But then in May the situation began to change. The Allies now benefitted from technological innovations: long-range aircraft equipped with radar and Leigh-Lights (powerful searchlights used in conjunction with radar), Huff-Duff, forward-firing mortars and the breaking of the German codes. And, thanks in large measure to Walker, a new spirit ruled in the navy. He advocated creating strike groups, which would not sail with convoys but act as a kind of maritime cavalry patrolling the sea. Walker was put in command of one of these elite units, which was at sea by the end of May.

Only a tightly disciplined and trained team, united by strong bonds, could operate in the manner expected by Walker. “I wish to impress on all officers,” he said “that, although I shall take charge in the majority of operations, I consider it essential for themselves to act instantly without waiting for orders in situations of which I may be unaware or imperfectly informed.” Photographs of Walker in the heat of an operation show a man animated by the thrill of the chase, surrounded by officers and men inspired by his élan and dedication. “We had the feeling we were almost invincible,” said one sailor.

The duel with U-202 called upon all that training and motivation. Walker’s tactic, when U-202 was relocated, was known by his men as the ‘boss’s special’. Three sloops carpet-bombed the area where U-202 lay submerged. Walker knew he was engaged with a master when the submarine survived this attack too. It was time for the ‘creeping attack’. Starling stationed herself a mile from the U-boat and Walker used his Asdic to guide two sloops, which had switched off their Asdic and cut their engines. Poser would have no idea of the stalking predators until the depth charges exploded.

But the young German commander kept changing speed and course. He also ejected 76 canisters, each of which released a stream of hydrogen bubbles. Asdic operators found it almost impossible to distinguish the echo from a sub and an echo from one of these bubbles; Poser would be able to slip away.

Luckily, Walker and his star team were blessed with the uncanny knack of telling a true echo from a decoy. U-202 could not escape the sound waves echoing off her hull. The attacks continued. Poser went down to 820 feet, where the boat was in danger of being buckled by the pressure. Poser’s only hope was to surface when his air ran out and scamper away in the night. Walker calculated the Germans would rise at midnight.

The time came and went. Then, at 00.02, a lookout spotted the U-boat. The group opened fire and U-202 was shattered. The survivors were rescued. “I am most grateful to Kapitänleutnant Poser for an excellent bit of Group training,” Walker commented in the laconic tradition of the Royal Navy. The hunt had lasted 14 hours. It was a textbook operation – the culmination of years’ worth of training. The admiral of Western Approaches Command signalled Walker: “I wish to congratulate your Asdic team on the most outstanding performance of the war.”

The Battle of the Atlantic was psychological warfare at its most intense. People in Britain suffered under the threat that food and fuel supplies would be cut off. But that sickening dread was beginning to subside. By mid-1943 methods pioneered by Walker sent morale in the German U-boat service plummeting. The deterrent effect was as important as the numbers of submarines sunk; U-boats could not operate with anything like the impunity they once enjoyed. Walker brought the fight right to the enemy’s front door, blockading the U-boats’ home ports in the Bay of Biscay.

Walker and his men gained national celebrity in February 1944 when they destroyed six U-boats in the course of a patrol, a record. Walker was hailed as Britain’s anti-submarine ace. The Times reckoned that he had been “more continuously in contact with the enemy at sea than almost any officer and man in the navy”.

But then, as he was about to depart again for the campaign in the Atlantic, he was taken to hospital suffering a cerebral thrombosis. He was bowed down from the struggle, and died at the age of 48. The Admiralty said that “Captain Walker, more than any other, won the Battle of the Atlantic”.

His memory was kept alive by those who served under him. In 1998 a statue capturing his drive was unveiled at Liverpool. But the final word should go to the man himself: “Please don’t call me U-boat killer number one. That formidable character is 1,000 British tars.”

The Royal Navy’s happy hunting ground

The Western Approaches were key to British naval success for 200 years

“The Boche… must be made to realise that the Royal Navy considers the Bay of Biscay a happy hunting ground and will stamp out any attempt to restrict the free and rightful passage of Allied shipping.”

With these words Johnnie Walker connected the Battle of the Atlantic with the history of the Royal Navy. The most vital waters for the fortunes of Britain were the Western Approaches, the area of sea from the northern coast of Spain to the western seaboard of the British Isles. Naval mastery depended on controlling this zone. It was Britain’s gateway to the world.

Anson and Hawke – two of Britain’s greatest admirals – brought the Western Approaches under the navy’s sway in the mid-18th century. They battled against scurvy, problems of supply and hazardous shores. Hawke’s ruthless blockade of the entire French Atlantic coast from 1758 was a triumph of leadership and organisation. It prevented invasion, crippled the French navy and gave the British the freedom to range the world.

The loss of control of these waters in the late 1770s brought the threat of invasion from a Franco-Spanish fleet and contributed to the loss of the American colonies. The spirit of Anson and Hawke was revived in the wars with Revolutionary and Napoleonic France by a series of admirals who maintained gruelling blockades of the Biscayan coast that proved decisive in achieving victory and transforming the navy into an unassailable force.

Campaigning in the Western Approaches tested seamanship and discipline to the limits. With groups led by officers such as Walker at large in the Western Approaches, German U-boats leaving La Rochelle had to hug the French coast and enter the Atlantic off the coast of Spain. Gaining the upper hand here was essential to achieving ultimate victory.
Ben Wilson is an acclaimed popular historian whose works include Decency and Disorder (Faber, 2008) and What Price Liberty? (Faber, 2009)


This article was first published in the August 2013 issue of BBC History Magazine