The Battle of the Atlantic
The battle for control of the Atlantic was one of the most important struggles of the war. Without the arms and supplies that came across the ocean from the United States, Great Britain was sure to lose. Winston Churchill was well aware of this, noting in 1940 that a minimum of twenty supply ships (approximately 120,000 tons of weapons and supplies) had to arrive in Great Britain each day if the country was to survive the German onslaught.
The Atlantic later became crucial to the United States as well, because its forces had to cross the ocean to bring the war to Germany and halt Hitler's aggression. As a result, the Battle of the Atlantic was one of the longest and most complicated of the war, costing thousands of lives on both sides and a tremendous amount of equipment and materials.
At the onset of hostilities, Germany made the Atlantic a top priority, with the navy and the Luftwaffe working together to make passage across the ocean as hazardous as possible. The German strategy was known as “tonnage warfare” and was based on the assumption that if 750,000 tons of British shipping could be sunk every month, Great Britain would be forced to surrender within a year.
Submarine Warfare Ensues
At the start of the European war in 1939, the German navy had just fifty-seven U-boats (submarines) available, twenty-six of them large enough to safely patrol the Atlantic. The average of twenty-three U-boats covering the Atlantic and the North Sea by September were able to inflict little damage because of recurrent torpedo problems and a lack of air reconnaissance needed to pinpoint potential targets. But the situation quickly grew more hazardous for Allied ships as these problems were fixed.
The first attack of the Atlantic campaign occurred on September 3, 1939, when the German submarine U-30 torpedoed the British liner Athenia, which carried more than 1,100 passengers. A total of 120 lives were lost, including 28 Americans. Had the country not been so firmly entrenched in isolationism at the time, the attack might have provoked the United States into war.
Shortly after, the British carrier Courageous was sunk by U-29, killing 519 men. When the carrier Ark Royal almost suffered a similar fate, the Royal Navy realized that using carriers and its few available destroyers to hunt Nazi subs was simply too ineffective and dangerous. The solution was to send merchant ships in convoys on the theory that there was safety in numbers. Nonetheless, German subs sank forty-one merchant ships by the end of the first month of the war.
Germany relied on both its submarine fleet and the Luftwaffe to help gain control of the Atlantic, but the Luftwaffe ceased to be a major factor in the sea war after June 1941 because it was needed more on the eastern front.
The situation got progressively worse, though the number of ships sunk declined briefly as the first fleet of subs returned to German naval bases to take on fresh supplies and restock their torpedoes.
In October 1939, the Royal Navy experienced a devastating blow when U-47 torpedoed and sank the battleship Royal Oak within the British base at Scapa Flow in the Orkney Islands off Scotland. The crew barely had time to react to the attack, and the ship sank quickly with her admiral and 785 crewmen.
Germany's Position Improves
The Battle of the Atlantic escalated with the fall of France, as Germany used the shores of the newly conquered country to launch submarine attacks in Atlantic shipping lanes. The French coast provided much easier access to waters frequently used by Allied convoys, and U-boat attacks increased accordingly.
Germany dramatically increased U-boat production as the war progressed, and soon Karl Dönitz, the German admiral in charge of the U-boat fleet, was able to again employ the “wolf pack” tactic he had used with great success in 1939. In the first use of the wolf pack strategy, four U-boats simultaneously attacked a convoy sailing from Gibraltar to England. Three merchant ships went down, and the convoy was forced to scatter. Dönitz realized immediately that the strategy could be very effective, though he did not have enough subs then to put it into full-scale use.
Though America was not officially at war with Germany during the early days of the Atlantic battle, its warships had frequent encounters with German submarines as the American ships assisted British convoys. On September 4, 1941, after Hitler declared the waters off Iceland a danger to Allied and neutral shipping, the U.S. destroyer Greer, sailing alone, made contact with and started following a German submarine off Reykjavik. The U-boat fired a couple of warning torpedoes at the Greer, which responded with depth charges. Neither ship was damaged in the incident.
A month later, the destroyer Kearny was struck by a U-boat torpedo while supporting a British convoy. The explosion killed eleven seamen and injured another twenty-four, but the ship was able to hobble to Iceland unassisted. Two weeks later, a U-boat sank the destroyer Reuben James off Ireland, killing all but 45 of the ship's 160-man crew.
The Battle of the Atlantic raged throughout the entire war, with the Allies the ultimate victors. However, the cost of that victory was tremendous. According to American military records, U-boats sank more than 3,500 merchant ships. Of that total, 2,452 ships were sunk in the Atlantic. U-boats also sank 175 naval warships serving as armed auxiliaries.
When the United States and Germany officially declared war on each other, American merchant ships were no longer protected by neutrality and became more frequent targets of German U-boats, particularly off the eastern United States and in the Caribbean. Allied antisubmarine efforts were extremely ineffective during the first months of the war. The first American victory over a U-boat didn't occur until March 1, 1942, when a navy ship sank the U-656.
The Battle of the Atlantic slowly escalated, with the Germans inflicting heavy casualties on Allied ships trying to bring much-needed supplies to England. Just in June 1942, the Allies lost more than 170 ships to German submarines, most of them in the western Atlantic.
The mass production of U-boats continued, and by March 1943 an estimated 400 German submarines were in service, more than 200 of them suitable for ocean patrol. The result was an almost constant harassment of Allied shipping and several major battles between U-boats and convoy defense ships. Many of these battles took a terrible toll on Allied naval defenses. During the first week of March, Convoys SC 121 and HX 229 both lost thirteen ships, HX 228 lost four, and SC 122 lost nine. By the end of the month, German submarines had managed to sink a stunning eighty-two ships in the North Atlantic and another thirty-eight in other waters. The loss of so many supply ships wreaked havoc in England, threatening its very survival. It also prevented the Allies from mounting any kind of major cross-Channel offensive into occupied France.
Just when all seemed lost, science came to the rescue. Allied ships began using a number of new antisubmarine technologies with remarkable success. The most effective was radar, allowing ships to detect subs in the area and mount a quick defense or, if undetected, launch an attack. In addition, advances in code-breaking technology enabled the Allies to monitor U-boat activity more effectively.
The Battle of the Atlantic ultimately went to the Allies, but the cost on both sides was high in terms of ships, equipment, and lives lost. For Great Britain, the victory at sea was painfully close. Noted Winston Churchill: “The only thing that ever really frightened me was the U-boat peril. I was even more anxious about this battle than I had been about the glorious air fight called the Battle of Britain.”
Within just a few months, the tide began to turn in the Battle of the Atlantic. Thanks to the new technology and additional support, the number of Allied ships lost decreased while the number of German submarines sunk skyrocketed. In May 1943, Convoy SC 130 was attacked by more than thirty U-boats over the course of its voyage, but it managed to sink five of them without losing a single ship. After that, Admiral Dönitz pulled his U-boat fleet out of the North Atlantic convoy routes, though he was certain that Germany would be able to counter the new technology with advances of its own in time.
One German countermeasure was the introduction of specially designed torpedoes that homed in on the sound of a ship's propeller, allowing more effective attack from a distance. However, these were soon countered with devices known as Foxers, which acted as decoys and drew enemy torpedoes away from ships.
Figure 4-1 Poster by Ben Shahn.
Photo courtesy of the National Archives (44-PA-246)
This give-and-take continued throughout the Battle of the Atlantic, with one side gaining a slight advantage only to be countered by a new strategy or new technology. For example, when Allied forces started using radarequipped aircraft to spot surface-cruising U-boats leaving French ports at night, Dönitz had his submarines fitted with antiaircraft guns and ordered them to travel on the surface during the day (when they could spot and shoot down enemy reconnaissance and attack planes). The Allies countered by attacking the submarines with larger, more destructive weapons. Dönitz eventually had his submarines outfitted with snorkels that allowed them to remain relatively submerged almost indefinitely. Dönitz also instituted a plan in which U-boats were provisioned and refueled at sea via special supply subs, though the Allies learned of the plan from broken German codes and quickly went after the supply ships.