(Part 5)World War II Full History

Code Breaking

During World War II, Germany believed that its secret codes for radio messages were indecipherable to the Allies. However, the meticulous work of code breakers based at Britain’s Bletchley Park cracked the secrets of German wartime communication, and played a crucial role in the final defeat of Germany.

The Enigma story began in the 1920s, when the German military - using an ‘Enigma’ machine developed for the business market – began to communicate in unintelligible coded messages. The Enigma machine enabled its operator to type a message, then ‘scramble’ it using a letter substitution system, generated by variable rotors and an electric circuit. To decode the message, the recipient needed to know the exact settings of the wheels. German code experts added new plugs, circuits and features to the machine during the pre-war years, but its basic principle remained the same.

The first people who came close to cracking the Enigma code were the Polish. Close links between the German and Polish engineering industries allowed the Polish Cipher Bureau to reconstruct an Enigma machine and read the Wehrmacht’s messages between 1933 and 1938. In 1939, with German invasion looming, the Poles shared their information with the British, who in turn established the Government Code and Cipher School at Bletchley Park in Buckinghamshire. Mathematicians and intelligence experts, with the help of primitive early computers, began the complex and urgent task of cracking the Enigma code.

The Germans, convinced their Enigma messages were unbreakable, used the machine for battlefield, naval, and diplomatic communications. Although the experts at Bletchley first succeeded in reading German code during the 1940 Norwegian campaign, their work only began to pay off meaningfully in 1941, when they were able to gather evidence of the planned invasion of Greece, and learn Italian naval plans for the Battle of Cape Matapan. In the autumn, the Allies gained advantage in North Africa from deciphering coded messages used by Rommel’s Panzer Army. Information obtained from such high-level German sources was codenamed ULTRA.

The Germans also enjoyed some noteworthy code breaking successes. The B-Dienst (surveillance service) broke British Naval code as early as 1935, which allowed them to pinpoint Allied convoys during the early stages of the Battle of the Atlantic. Although the US altered its naval code in April 1942, the change came too late to prevent the havoc wreaked by Operation Paukenschlag, the German U-boat campaign off America’s east coast early that year. The Germans also managed to crack Soviet and Danish code systems. But their efforts – fragmented and divided between rival cryptology departments - lacked the consistent success achieved at Bletchley Park.

From 1941 onwards, Bletchley’s experts focused upon breaking the codes used by German U-boats in the Atlantic. In March 1941, when the German armed trawler ‘Krebs’ was captured off Norway complete with Enigma machines and codebooks, the German naval Enigma code could finally be read. The Allies could now discover where U-boats were hunting and direct their own ships away from danger.

The German Navy, rightly suspicious that their code had been cracked, introduced a fourth wheel into the device, multiplying the possible settings by twenty six. The British finally broke this code that they called ‘Shark’ in December 1942. Using ULTRA always presented problems to the Allies, because any too blatant response to it would cause the Germans to suspect their messages were being read. But neverthless Bletchley Park and its staff made a crucial and groundbreaking contribution to the defeat of the Axis.

Battle of the Atlantic

The Battle of the Atlantic, which lasted from September 1939 until the defeat of Germany in 1945, was the war’s longest continuous military campaign. During six years of naval warfare, German U-boats and warships – and later Italian submarines – were pitted against Allied convoys transporting military equipment and supplies across the Atlantic to Great Britain and the Soviet Union. This battle to control the Atlantic shipping lanes involved thousands of ships and stretched across thousands of perilous square miles of ocean.

Early in the war German warships made a number of forays into the shipping lanes, aiming to catch and destroy Allied convoys. These had limited success, and led to the loss of major ships including Graf Spee and Bismarck. From 1940 onwards, the German navy focused on escalating the U-boat war. Attacking on the surface at night (where they could not be detected by Allied sonar, or ASDIC), U-boats had great success against Allied convoys, sinking merchant ships with torpedoes and then submerging to evade the counterattack by escorting warships. They were also benefitting from decoded communications of the British Admiralty. In 1941 they inflicted huge losses, sinking 875 Allied ships.

During 1941, tactical advantage began to shift towards the British. They had received 50 American destroyers in exchange for US access to British bases. Canadians increased their escort missions, and RAF Coastal Command was able to increase its air cover. The capture of U-110 (complete with Enigma machine and codes) in March 1941 helped the Allies track the movement of German U-boats. From April 1941, US warships began escorting Allied convoys as far as Iceland, sparking a number of skirmishes with U-boats. This provoked controversy as the US had not officially entered the war. Technological developments, including radar for escorting warship from August 1941 (which could detect a U-boat periscope at a range of one mile) also worked in the Allies’ favour.

Yet convoys were still very vulnerable in the ‘Atlantic Gap’, a ‘black pit’ in the mid-Atlantic which was not covered by anti-submarine aircraft. The gradual improvement of antisubmarine techniques, and the increased use of improvised aircraft carriers like HMS Audacity, led to a marked decrease in sinkings towards the end of the year. This contributed to Hitler’s decision – carried out against Dönitz’s wishes - to transfer submarines to the Mediterranean.

In 1942 the balance tilted once again in favour of the Germans. New submarines were entering service quickly, at a rate of 20 per month. Although the US Navy entered the war at the end of 1941, it was unable to prevent the sinking of almost 500 ships between January and June 1942. Allied losses in the Atlantic reached their peak in 1942. As 1,664 ships were sunk, supplies of petrol and food to Britain reached critically low levels.

In 1943, advantage shifted to the Allies once again. By now, the Allies had sufficient escort aircraft carriers and long-range aircraft to cover the Atlantic Gap. The battle reached its peak between February and May 1943. The ‘hedgehog’ depth-charge mortar was just one innovation that was making life more and more dangerous for U-boat crews. By ‘Black May’ of 1943, U-boat losses were unsustainable – one quarter of their strength in one month, and almost at the same rate as Allied shipping. U-boats were withdrawn from the Atlantic, and the battle was won. Although new German submarines arrived in 1945, they came far too late to affect the course of the battle.

Historians estimate that more than 100 convoy battles took place during the war. They cost the Merchant Navy more than 30,000 men, and around 3,000 ships. The equally terrible cost for the Germans was 783 U-boats, and 28,000 sailors.

North Africa

When Italy entered World War II in June 1940, the war quickly spread to North Africa, where her colony of Libya bordered the vital British protectorate of Egypt. On 7 September 1940, Marshall Graziani’s troops began a land offensive. Their numerical supremacy won them initial success. They captured the port of Sidi el-Barrini and established a chain of fortified camps. The British counterattack, launched in December 1940 and led by General Wavell, quickly flattened the Italians. As British armaments grew daily, Italian supplies dwindled. Italian forces retreated in chaos, and the human tide of surrendering soldiers impeded the Allied advance, making movement of tanks difficult. With Italian positions crumbling, Hitler, shocked by the Italian failure, dispatched the German Afrika Korps – commanded by the brilliant General Erwin Rommel.

The ‘Desert Fox’ rapidly adapted his formations and tactics to a Desert War fought in the open, with few natural obstacles and a small civilian population. Rommel launched his first blow against the Allies in February 1941, taking the British by surprise and carrying out an audacious triple attack on the Sollum-Halfaya line on the Egyptian border. The Germans captured the key port of Benghazi, moving on to besiege the other major port of Cyrenaica, Tobruk.

In June 1941, Operation Battleaxe, the British attempt to liberate Tobruk, was stopped in its tracks by well-prepared defences. In November, with General Auchinleck having replaced Wavell, the Allies launched Operation Crusader, catching Rommel’s forces by surprise. Although German 88mm guns wreaked havoc among the British ranks, Axis forces – under the pressure of huge losses and dwindling supplies – were forced to retreat to El Agheila - their starting-point in March. At the end of 1941, Tobruk was liberated and Benghazi returned to British hands.

Supplies were a crucial element of the war in North Africa. While the British received material from depots in nearby Alexandria, German supplies had to arrive from Tripoli. Furthermore the island of Malta, Britain’s ‘unsinkable aircraft carrier’, allowed attacks to be made on Axis convoys crossing the Mediterranean. At the beginning of 1942, British supply lines were now overextended, and Rommel counter attacked, forcing the British to retreat to the defensive positions known as the Gazala Line. The Battle of Gazala - one of the fiercest of the Desert War – resulted in the retreat of Auchinleck’s men to Alam Halfa. Tobruk, cut-off once again, this time fell rapidly to Axis forces.

A disconsolate Churchill reshuffled the military command, placing Montgomery at the head of the Eighth Army. The battle-hardened general, conscious that the mobile tank battle was Rommel’s forte, unleashed the Battle of El Alamein as a battle of attrition, using his huge advantages in artillery, infantry and supplies. After two weeks of intense fighting, Commonwealth forces had reduced the German tank force to 35, pressuring the remnants of Axis forces into retreat.

For the Axis, the nail in the coffin came in November 1942 with Operation Torch - the American-led landings in Algiers, Oran and Casablanca. After sporadic fighting against Vichy French forces, the Allies took possession of the Moroccan and Algerian coasts. The beleaguered Axis forces were now encircled, and in May 1943, more than 230,000 troops surrendered to the Allies in Tunisia, marking the end of the campaign.

Credit to: http://www.history.co.uk for my source of this story