As the Allied convoys pushed across the Atlantic, some heading into the arctic, the conditions for the crews could be merciless: they were cold (and not just cold, but cold), famished, and terrified. Beneath the waves, sometimes whipped up by storms so savage that heavy merchant vessels were forced backwards, there lurked seek-and-destroy “wolf packs” of German U-boats. It could get so cold, that crews would have to clear ice from their ships to stop them capsizing (“One night it was so cold the flame on my lighter froze,” joked Only Fools and Horses' Uncle Albert about life on the convoys).
If the weather was clear, it was even worse: the conditions made it easier for the U-boats to find and attack them. But life for the German submariners wasn’t much easier: crammed into uncomfortable, airless U-boats with the harrowing knowledge that they likely wouldn’t survive the war. Of the 38,000 men who served in the U-boats, only 8,000 lived to tell the tale.
The Battle of the Atlantic raged for six years across the cruel, perilous ocean – a fight to control the all-important sea channels. It's the setting for the latest Tom Hanks film, Greyhound, directed by Aaron Schneider and scripted by Hanks himself.
Based on The Good Shepherd by C.S. Forester, it sees Hanks play Captain Krause, charged with protecting a convoy of 37 Allied ships that come under attack, armed with faltering equipment, steely nerves, and back up from the ever brilliant Stephen Graham. It's a fictional story, but the film is appropriately designed as a taut, desperate, technical thriller – Sailing Private Ryan, if you like.
It is perhaps surprising that the Battle of the Atlantic has been so underserviced on the big screen (or even the small screen – Greyhound has been rerouted from cinemas to Apple TV amid the Covid-19 crisis). But it was a long, complicated and miserable campaign that saw the Allies eventually triumph in increments – not exactly easy to boil down to 90 minutes or so.
As the wartime legend goes, it was Churchill himself who coined the term “The Battle of the Atlantic”, a supposedly deliberate invocation of the Battle of Britain. Because like the Battle of Britain, victory was paramount in Blighty surviving the Second World War.
The supply routes across the Atlantic were absolutely crucial. Seventy percent of Britain’s food was imported; plus, precious metals and materials used for essential manufacturing.
Historian GH Bennett wrote that the famous “Dig for Victory” and “Make Do and Mend” campaigns were intended to take the strain off demand for supplies from across the pond. “The Atlantic was a lifeline,” said historian Jonathan Dimbleby in 2015. “It was the carotid artery on which Britain depended for survival and its capacity to prosecute the war.”
Indeed, Churchill claimed that the “U-boat peril” was the only thing that truly frightened him during the war. Not only was the Atlantic supply route crucial to the survival of both Britain and Russia, but the effects of the battle reached way beyond the ocean itself. Without an Allied victory in the Atlantic, there may have been no victory in the Mediterranean, no supply routes from the Middle East, no D-Day, and no bombing campaign in Germany.
“Some people say the Germans were defeated on the Eastern Front,” says Philip D Grove, a naval historian and lecturer at Britannia Royal Navy College. “But it’s the Atlantic that decides everything. Fundamentally, the western theatre is dependent on gaining control of the Atlantic and enabling the supply of goods.”
It could also have been a very different war for the Americans. “If Britain had fallen, America would have faced a two-front war on its own,” says Grove. “That would have extended the Pacific campaign, and probably the European campaign to defeat the Nazis. And if they’d hadn’t been able to, our global history would be different. Maybe not quite The Man in the High Castle-different, but different to the world we live in today.”
The Battle of the Atlantic began on September 3, 1939 – just hours after Britain declared war on Germany – when the U-30 torpedoed the SS Athenia in the Western Approaches, as it travelled from Liverpool to Montreal, killing 117 civilian passengers and crew.
Neither side’s navy was adequately prepared for the impending battle. The Royal Navy had, according to Jonathan Dimbleby, “misread” the lessons of the First World War and underestimated the U-boats. So did Grand Admiral Erich Raeder, the head of the German Kriegsmarine, who wanted to fight the war with surface vessels..“He wanted battleships, battle cruisers, destroyers, and aircraft carriers,” says Grove. “It was partly for status, and to challenge the Royal Navy.”
Living conditions on both sides were grim. There was little to do on Allied ships except wait fearfully for the next long-range sneak attack from a German torpedo. Life on board the U-boats was arguably even worse, with no fresh air, sanitation or heating, and a maximum of two toilets for the whole crew.
Rear Admiral Karl Dönitz, commander of the submarine fleet, knew the destructive potential of the U-boats, and requested a fleet of 300. But he was refused. When war broke out, there were only around 50 in use – only around half of which were long-range and seaworthy. (“That’s not many submarines to take to the world’s biggest merchant marine on the global stage,” says Grove.) And the Type VII U-boats, the backbone of the fleet, only carried 14 torpedoes and had to be armed with deck guns.
“German submarines in both world wars often attacked from the surface at night, using the guns,” says Grove. “It was to save their precious torpedoes for high value targets.”
The Germans had just 13 submarines in the Atlantic at any given time during the first year of the war. But still, the U-boats had significant early success. By December 1939, U-boats had sunk over 100 merchant vessels. Crucial supplies of food and metals were lost to the ocean. In June 1940, they gained a further advantage when the Nazis took hold of the French ports, giving them access to the North and South Atlantic.
The British Navy made a decision early on to group merchant ships into convoys, which included oil tankers, cargo liners, tramp steamers, coasters, and colliers. They would be escorted by destroyers, frigates, corvettes and other large vessels. Thousands of merchant ships were also fitted with defensive guns. The early convoys from North America were escorted by the Canadian Royal Navy; at home, with resources divided between the Atlantic and Europe, there simply weren’t enough ships to go around. It was a “tonnage war”: if the Germans could sink more ships than the British could rebuild, the Battle of the Atlantic would be won.
A major problem, as seen in Greyhound, was the “mid-Atlantic gap” – called “The Black Pit” in the movie – an area which couldn't be reached by short-range aircraft to help defend the convoys.
“To begin with we didn’t have enough escort vessels and didn’t have the range,” says Grove. “The Canadian Navy, which was small to begin, would escort the convoy into the western side of the Atlantic but would have to give up, and the convoy would sail on its own, either together or by splitting up. Then on the eastern side of the Atlantic, the Royal Navy would pick it up and bring it into British harbours.”
It was in late 1940 that the U-boats began to have major success operating in wolf packs – surfacing in groups and attacking at night. The tactic reduced the effectiveness of ASDIC, a sonar which only detected U-boats underwater.
In September 1940, Churchill struck a deal with Roosevelt for the use of 50 US destroyers. That same month a U-boat torpedoed the SS City of Benares, which was transporting civilians from Liverpool to Canada to escape the Blitz. In total, 260 people drowned – 77 of them children.
As detailed by historian Gavin Mortimer, 128 merchant ships and 700,000 tons of supplies were sunk between August and October of 1940. The period between late 1940 and 1941 was known as the “happy time” for the U-boat arm.
The British had success in March 1941 when the destroyer HMS Vanoc sunk U-100. It had found the U-boat using a seaborne radar, one of numerous technical innovations that would eventually tip the balance, including radar, sonar, high frequency direction-finding, and Enigma code-breaking. The Royal Navy also had success in the surface battle too: in May 1941, the Bismarck – the German fleet’s most famous battleship – was sunk.
By September 1941, US ships were involved in the Atlantic – three months before the attack of Pearl Harbor officially brought the Americans into the war. US ships were even fired on by Germans and in October 1941, the USS Reuben James destroyer was sunk, killing 100 men.
“American neutrality before December 1941 is a bit of a myth,” says Grove. “Roosevelt knew that the war was coming. He was also aware that Britain needed as much help as possible. As early as 1940, American exchange officers were working alongside the British – most famously in the hunt of the Bismarck in 1941. The Americans started taking a firmer line. They started to convey, augment and replace Canadian ships that were escorting the convoys to Britain.”
When the US officially declared war, much of the responsibility for escorting convoys was handed back to the expanding Royal Canadian Navy. The U-boats moved towards the east coast. With no convoy system in place, US ships were picked off by a handful U-boats – a period known as the "second happy time".
“They kind of ignored our advice,” says Grove about the US naval commanders, “and they mostly got hammered off the American coast.”
In 1942, half of the tonnage lost in the entire war was sunk. “This is when Churchill says nothing scared him more,” says Grove, “and you can see why when he starts to lose millions of tons of shipping.” By 1943, the German navy had begun rectifying its problems: more submarines, better torpedoes, and some air support. They sunk 101 vessels in January and February. In March, three U-boat wolf packs attacked two convoys, costing the Allies 22 ships, 41,000 tons of cargo, and over 300 merchant sailors.
But the German fleet soon found itself facing an insurmountable opponent: American industry. “By 1943, American shipyards were able to replace everything the Germans had sunk and build more on top of that,” says Grove. “Their productivity was insane. The Americans produced 50 percent of everything produced in World War Two. Many of the ships they produced were Liberty and Victory class ships – a British design. We wanted the Americans to build 60 to replenish our merchant marine. They built over 2,700. And that’s just what was being built in American shipyards.”
Also crucial was the introduction of VLR (Very Long Range) Liberator bombers. At first, the Air Ministry withheld the bombers from the Admiralty, with Arthur "Bomber" Harris wanting to keep them for the campaigns against German cities and industrial targets.
“Churchill invariably sided with Harris, until very late in the day, thus prolonging the Battle of the Atlantic by at least a year,” said Jonathan Dimbleby. “As a result a great many ships were sunk and lives lost unnecessarily. Churchill was a great war leader but this was a great error, the greatest, in my view, of his entire leadership between 1940 and 1942.”
It took a modest allocation of just 39 of these long-range bombers to change the battle. Capable of flying 1,000 miles into the Atlantic, they carried radar and anti-submarine weapons, and forced the U-boats back underwater.
Dimbleby also detailed the difficulty of breaking the Enigma codes. The British had captured an Enigma machine from the U-110 in May 1941 (though Hollywood would have you believe it was Jon Bon Jovi who found it, on the U-571). The naval Enigma codes were tougher to crack and in January 1942, the Germans installed a fourth “rotor”. It took 10 months to crack the new codes – and even then, German intelligence intercepted Royal Navy messages. “A kind of blind man’s buff went on,” said Dimbleby.
The changes in technology and production created what Grove calls "a see-sawing battle" – the convoys became U-boat killing zones if found.
“Western technology – particularly British technology and innovation – combined with American production, really signaled the death kneel of the submarine threat in the Atlantic," says Grove. "The Allies were able to finally defeat the U-boats by May 1943. That month, some 41 U-boats were sunk – a totally unsustainable number that led to their withdrawal.”
Across April and May 1943, 56 U-boats were lost. Among the casualties was Karl Dönitz’s own son. The Battle of the Atlantic did continue until the end of the war, but the German power was greatly diminished. Philip D Grove points towards the Das Boot TV series for an accurate depiction of what it must have been like for the German submariners: “As the war goes on, the life of the submariner becomes ever more horrid. As they set sail in 1943, ‘44, and ‘45, they know they’re probably not coming back. Over three quarters of German submariners never returned.”
Towards the end of the war, the Germans produced upgraded Type XXI and XXIII U-boats, which could have been devastating if introduced earlier – perhaps when Dönitz had requested a bolstered fleet.
Eighty percent of the convoys made it across the Atlantic unscathed, but between 75,000 and 85,000 Allied seamen were killed. And more than 30,000 of them were merchant sailors – some of the unsung heroes of the Second World War. “We often forget the plight of the merchant mariner,” says Grove. “As many merchant mariners died in World War Two as Royal Navy personnel. Their existence was essential for our survival.”
As Jonathan Dimbleby said: “It’s impossible to understand the Second World War without appreciating the Battle of the Atlantic.”
Greyhound is available on Apple TV from July 10