The changing nature of America's involvement in World War II is an interesting strategic story because the American people were weary of war and during the time Hitler was taking over one European nation after another. After the attack on Pearl Harbor of course Americans were fully ready to go to war with Japan. But the situation in Europe was not as well defined as far as American involvement. And the Battle of the Atlantic was, in reality, a "…battle to deliver supplies" and in fact "…the future prosecution of the war" depended on the success of this battle (www.ibibilo.org). This paper reviews the strategies employed by the U.S. And Great Britain, the technologies used, and other aspects of the Battle of the Atlantic.
Why was the Battle of the Atlantic important?
The importance of winning this battle -- which the allies won, with an enormous military, technological and strategic effort provided by the United States -- cannot be understated. England was being bombed daily and the Germans had control over most of Europe. The beginning of this pivotal, seemingly endless battle -- the longest battle in WWII -- was launched by the German U-boats, as they attacked unarmed ships that were bringing supplies to England and other allies in Europe. It became clear to American strategists and to England that unless America came to the rescue, the Germans could (and very well might have) seized England as one of their more impressive prizes. The Battle of the Atlantic lasted six years, and during those years, "…thousands of ships were sunk and tens of thousands of men were killed in the Atlantic Ocean," according to the Destroyer Escort Historical Museum in Albany New York (www.ussslater.org).
This was a crucial battle because Allied supply ships and merchant ships needed to be protected by escort ships, and despite the German U-boat challenges, supplies were urgently needed so the United States began using "neutrality patrols" to protect ships that were carrying critical supplies to our oldest ally, England. As an example of how dangerous it was for American supply ships to cross the Atlantic carrying pivotal supplies, between January and December, 1942, "German U-boats and aircraft sank over 1,000 Allied ships both in the Atlantic and off the East Coast of the U.S." (www.ussslater.org).
Hitler's Plan to Cut Off England
It was the original plan of Hitler's commander in charge of U-boats, Admiral Karl Donitz, to have 300 U-boats ready for the outset of war with the allies. But only 57 U-boats were in fact in the water when the decision was made to begin sinking all ships (merchant and supply ships sent to bail out England), according to the History Place. And when German Naval Intelligence broke the British Royal Navy's radio communications, it gave the Germans a huge early advantage because they knew in advance when convoys would be moving towards England. When ships was attacked by a torpedoes, "…hundreds of men drowned in the bone-chilling Atlantic or burned to death in the floating pools of flaming gasoline" (History Place, 2010).
However, when long-range radar devices were invented, and installed on British bombers, the allies were able to "pinpoint the far off positions of the U-boats" as they traveled on the surface. Those bombers began destroying U-boats with 300-pound depth charges and soon after (in 1943) American B-24 bombers also "…roared into the air from British land bases" and, because they too were equipped with radar, the tide was beginning to turn against Germany (History Place).
Allied Technologies / Intelligence
One of the most important captures in the Battle of the Atlantic -- which was an enormous boost to the allies' intelligence efforts -- was the seizure of U-505, a submarine that was attacked and taken in June, 1944. The U.S. destroyers forced the submarine to surface then sailors boarded the vessel and towed it to Bermuda. There, the Enigma code machine was discovered and the "…code books to go along with the machine," which allowed America and its allies to "begin cracking German codes with great success" (www.ussslater.org). Soon, many radio transmissions from Germans were intercepted thanks to the allies' cryptographers' ability to easily decode those transmissions.
In the site titled "Allied Communications Intelligence December 1942 -- May 1945," the author points out that "…well over 115,000 individual German naval messages were decrypted in OP-20 and read in the Atlantic section" (www.ibiblio.org). Looking specifically at dates, the site explains that during the first nine and a half months of the allies reading the decryptions (from December 1942 to mid-September 1943), it was not always "solid" decryption that was accomplished.
Moreover, often the decryption technologies were not as timely as they needed to be, for "operational effectiveness" (www.ibiblio.org). But in 233 of the 289 days in that window of time, encryptions were read, and in one five-day period, allies decoded 127 German messages (and in 2 of those 5 days allies effectively intercepted 61 German war messages) (www.ibiblio.org). But as the decryption technologies were perfected, the U-boat effectiveness was severely compromised; in fact between mid-September 1943 and the end of the war with Germany (May, 1945), "…it is no exaggeration to say that U-boat traffic was consumed on the spot, continuously, solidly, and currently for 19-1/2 months" (www.ibiblio.org).
Exactly what German radio communications that were decoded by the allies were most meaningful in terms of knowing what the Germans U-boats were going to do? First, the communications to U-boat commanders gave "heading points and operational plans" -- which of course was vital information for the allies. Secondly, the U-boats were ordered to send "passage reports" once they cleared outer Biscay (France) or were headed out into the Atlantic; and third, the radio communications intercepted gave the allies exact information as to where the U-boat was assigned to go (www.ibiblio.org).
In addition U-boats transmitted their positions, their time of arrival at their next appointed position, how much fuel was on hand at the time, and even the "…enemy's temper could be determined, his habits and character appreciated" (www.ibiblio.org).
As for other technologies that were developed by the allies, one very important development was RADAR, which was used to detect German vessels on and above the seas. Also, the allies developed High Frequency Radio Direction Finding (HF/DF), which was "…a means of detecting vessels" and doing it with "extreme precision" (www.marinersmuseum.org).
Meanwhile, Kennedy Hickman writes in the New York Times-owned publication About.com about how technology helped turn the tide in the allies favor. There was one very important convoy (ONS 5) that was protecting merchant and supply ships; that convoy was severely harmed in April, 1943 when "…30 U-boats" attacked the convoy and sunk 13 ships (Hickman, 2014). But two weeks after those 13 ships were torpedoed and destroyed, another convoy (SC 130) did indeed "repel German attacks and sunk five U-boats while taking no losses" (Hickman, p. 2). How could this have turned around so quickly for the allied forces?
This turnaround was due to the "…integration of several technologies which had become available in the preceding months," Hickman continues (p. 2). One of those technologies was the "Hedgehog anti-submarine mortar," and combined with advances in decoding German radio communications (mentioned earlier in this paper), and "enhanced radar," the allies were now on the offensive against the U-boats (Hickman, p. 2). In addition, the allies had the "Leigh Light," which gave aircraft the ability to spot U-boats at night. The tally for the month of May in 1943 was 34 U-boats sunk; that wasn't an entirely harmless month though as 34 allied ships were also sunk.
The advantage of having "superior intelligence" as to the whereabouts of the enemy, and what the enemy was planning to do, was of "vital significance" (www.ibiblio.org).