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The initial British victory in Africa was overcome by Rommel, who by year's end had pushed them back into Egypt. There were new partners on both sides of the fence - the Japanese had joined the Axis and embarked on conquest in the Far East, and the United States had joined Great Britain. The conflict now ranged globally on all the oceans of the World. The United States was determined to help the British fight Hitler, at the same time waging war against Japan.
Coded messages were being passed back and forth between headquarters and field units by both Allies and Axis. The British were reading German codes; The Germans in turn were snooping on the British, and the Americans were listening in on the Japanese. Decodes obtained at England's Bletchley Park (BP) were called "Ultra"; The Americans termed their break into Japanese codes "Magic."
The Germans soon realized that daylight bombing attacks on England were far too costly, and developed methods to guide bombers which did not depend on seeing the ground. In 1940 British anti-aircraft guns were practically useless, their night fighters converted slow and obsolescent twin-engined Bristol Blenheims. A network of ground-based radar stations warned of incoming aircraft, but there was no airborne radar. Defenders had to be guided to the general area of an attack, and rely on visual sighting. Frequent cloud cover in winter often made this impossibly difficult.
The Germans used a Lorenz system in reverse; instead of guiding a plane to a runway, it was led away from the runway and towards the target. The usual blind landing system had a range of 30 miles, but the Germans had fitted their bombers with ultra-sensitive receivers.
Proessor F. A. Lindemann, scientific advisor to Winston Churchill, maintained that such a beam could not follow the curvature of the Earth. Dr. R. V. Jones of Air Scientific Intelligence believed the evidence showed otherwise.
Documents retrieved from downed German bombers showed that the beams operated on a frequency of 30 mhz. The only device capable of detecting this was an American "ham" receiver, the Hallicrafters S-27. Fitted to a search aircraft, the beam was detected. The Germans made this work easier by testing their system over England instead of Germany. Knickebein was called "headache" by the British, and jammers dubbed "aspirins" were developed. Soon German bombing accuracy diminished due to the interference.
The Germans developed a technique which would turn against them later in the war. A small flight of planes with crews skillful in following the beams led the flight, dropping incendiary flares to mark the target. The British countered with "Starfish" - decoy fires lit to lure the main mass of bombers.
By March 1941 all three beam systems had been rendered ineffective, and RAF night fighters equipped with airborne radar were downing bombers in significant numbers. The British wondered what new electronic wizardry they might have to combat next, when the bombers stopped coming. They were now being sent to Russia.
The British presumed that Bismarck was either on her way to Norway or the Atlantic, and a large number of ships were deployed in an attempt to locate her. Not knowing that the British had lost him, Admiral Lütjens assumed they knew where he was. He transmitted a coded message detailing his shortage of fuel and that his destination was France.
The code used was not readable by BP, but the length of transmission afforded plenty of time to obtain RDF fixes on his position; however, the report was somehow mishandled, and British forces went searching in the wrong direction.
A cardinal rule in sending coded messages is never to transmit the same text in two different ciphers, because if one is known, the message can afford a break into the other. In a response to an inquiry from Luftwaffe Chief of Staff General Hans Jeschonnek, who may have had a relative on board Bismarck, the message was repeated in the Luftwaffe cipher, which the British could read.
This confirmed his position, and he was sighted 700 miles west of Brest. Bismarck was attacked by aircraft from HMS Ark Royal. A single hit damaged a propeller and the rudder, cutting her speed to a crawl and causing her to steam in circles. Attacked by various ships, Bismarck was scuttled by her crew on May 27.
One more large warship, so beloved by Hitler and Raeder, often at the expense of Dönitz' submarines was out of the picture.
One of the last messages from the stricken ship read:
KRKRX FLOTT ENCHE FANAN OKMM XXTOR PEDOT REFFE RACHT ERAUS XSCHI FFMAN OEVRI ERUNF AEHIG XWIRK AEMPF ENBIS ZURLE TZTEN GRANA TEXES LEBED ERFUE HRERX
"Commander-in-Chief Fleet to Naval Headquarters: Torpedo hit right aft. Ship unmaneuverable. We fight to the last shell. Long live the Führer"
Enigma messages were separated into 5-letter groups for transmission. KR (Kriegstelegram, war telegram), twice repeated at the start, indicated an important message and told other operators to clear the airwaves. Next was AN (to) or VON (from), often repeated twice. Thus ANAN OKMM signified "To Naval Command" (Oberkommando des Marine). X was a stop (period), XX a colon and Y a comma. X's were frequently scattered at random throughout messages to foil attempts at decoding.
Stalin was duly warned, but the British could not reveal the source of their information, for fear that the Germans would realize their coded messages were being read. Stalin, perhaps in the belief that England was trying to drive a wedge between Russia and Germany, ignored the warning, although he must have had intelligence from other sources as well.
Although the British believed that Russia could not survive very long under the German Blitzkrieg, they welcomed the respite, as German forces were drawn to the second front.
In August, 1941, the first convoy sailed for Russia. By the end of the year, eight convoys had made the trip without a single loss, although in appalling conditions of ice, fog and terrible storms; Dönitz was concentrating his forces on England's supply line. The Allied strategy depended on Russia waging a war of attrition with Germany until forces could be marshaled for an invasion of France. As might be imagined, Stalin was not exactly thrilled at the prospect of being a sacrificial lamb.
In 1941 Dönitz adopted the Rüdeltaktik (literally, "pack tactic" but called "wolf pack" by the Allies). A picket line was set up perpendicular to the assumed path of the convoy. B-Dienst was reading the convoy code, so knew their course. Also, to conserve fuel, the ships traveled along predictable great circle routes as well. The first boat to sight the convoy radioed the position to U-Boat headquarters, which sent a radio message to the rest of the pack to converge on the luckless prey.
BP could not read the U-Boat code, Schlüssel-M, but RDF (Radio Direction Finding) allowed several receiving stations to take "fixes" on the subs, although this technique was not very accurate.
Wing Commander Leigh of the Coastal Command proposed placing a powerful movable searchlight in the nose of the plane to illuminate the submarine at night. After the usual considerable battles with officialdom, the Leigh light was adopted. The surfaced sub was acquired on radar, and when contact was lost at about a mile the light was switched on. The effect on a submarine crew was considerable - cruising along with no warning, a blinding 22 million candlepower light, and the depth charges.
As with any new weapon, it is only effective until a countermeasure is developed. The Germans soon equipped their subs with "Metox" receivers, which picked up the radar pulses, and gave plenty of warning to dive to safety.
Blocked from expansion to the north by Russia, the only way was south and east. I n Europe, the French and Dutch had been defeated, Great Britain had her hands full with Germany, so the Dutch East Indies Malaya and Borneo, with their rich supplies of oil and rubber, were quite tempting. The die was cast when the U.S., miffed at the Japanese refusal to withdraw from China, cut off oil exports and froze Japanese assets.
1942 brought astounding victories to the Japanese. Manila fell Jan. 2, Corregidor and the Philippines on May 6, Singapore by Feb. 15, The Dutch East Indies and Rangoon were occupied early in March. From January through March Burma, Rabaul, Hong Kong, Singapore, Timor, Java and Borneo were theirs. On February 19, 1942 the harbor at Darwin, Australia was bombed. They soon controlled a vast area ranging from the Aleutians to the Gilbert Islands through Java, a rough semi-circle extending some 6,000 miles. Their advance had been so fast and furious even they were surprised.
Merchant ships, including tankers loaded with aviation fuel, blithely steamed up the east coast of the United States to rendezvous at the starting points of the North Atlantic convoys. They were perfectly silhouetted against the blazing lights of cities from Florida to Maine. Residents of east coast cities often woke to find their beaches inconveniently littered with corpses of merchant mariners.
In December, 1941 only 50,000 tons were lost to U-boats in the North Atlantic, partly because BP was reading the Atlantic U-Boat's cipher, Hydra. February 1 Hydra was replaced by a new cipher, Triton, and BP was unable to decode U-Boat messages for the next ten months. Between this, and the carnage on the U.S. east coast, the monthly total for March jumped to 500,000 tons.
BP was not completely blind, however. Although they couldn't read U-boat messages, they were able to decode a number of transmissions to and from ships escorting them through minefields in and out of port.
By May 1942 thirty U-Boats were operating off the U.S. eastern seaboard, but the Americans were finally getting their act together, implementing ASW and convoy tactics. By July, Dönitz had 140 operational boats, although some were siphoned off to Baltic and Mediterranean operations.
Bomber command insisted that Germany could only be brought to its knees by destruction of its industrial production, ignoring the U-Boat threat to England's life line. There was an element of pride involved; bombing Germany proper was an offensive action, sinking U-Boats was purely defensive. Unfortunately, Germany was winning its battle, England was losing hers.
Since the source of their intelligence could not be revealed, the British arranged search aircraft to "spot" the ships. Shortly thereafter the Navy showed up to send the convoy to the bottom. One day, in a fog so dense that spotter planes could not possibly see anything, the Navy showed up with the usual result. Kesselring sent an urgent message to the Abwehr (Military Security Service) in Berlin, calling for an investigation into the cause of the intelligence breach.
The British, reading this also, directed a message to Naples in a cipher they knew the Germans could read, congratulating a non-existent secret agent on his fine work, and offering him a bonus! The Germans were reassured that their codes were safe, and accused the Italians of perfidy.
Although Rommel was short of supplies, he overstated his case in desperate messages to Kesselring, hoping to get at least part of what he asked for. Winston Churchill, reading Rommel's frantic pleas for help, urged Wavell to attack immediately. Wavell, realizing that Rommel's true position was not nearly as desperate as what he was radioing to Kesselring, declined to engage. Wavell was summarily replaced by General Sir Claude Auchinleck, and finally by Field Marshal Sir Bernard Law Montgomery, whose tactics were more to Churchill's liking.
August 13, 1942 a disastrous attempt was made at an amphibious landing on the French coast at Dieppe. 6100 troops were landed to test the German defenses. The attack was made at the point of strongest defense, rather than from the flanks. The result was a complete and dismal failure; casualties among the Canadians amounted to 68%. However, valuable lessons were learned in tactics and design of landing craft.
Dönitz' U-Boats had fortunately been distracted by a convoy from Sierra Leone to England, although 13 ships of that convoy were lost. 340 ships steamed through the Straits of Gibraltar on November 5, with the Axis caught by complete surprise. Ultra intercepts revealed no hint of German suspicions that North Africa was the target; Malta and Sicily were being mentioned.
Opposing the Allied landing were forces of the Vichy French, Italians, and, of course, the Germans. Italian morale was believed to be low, and the French (in particular, their Navy) was an unknown. Would they join the Allies, or oppose them? November 7 the Allies landed, unopposed except for resistance in the ports of Algiers and Oran. The French question was settled when the Allies were welcomed, and Admiral Darlan defected to them.
Rommel was deprived of information on Allied intentions when his intelligence unit was captured July 10, 1942, and the Allies immediately changed their codes. Without intelligence, and running low on fuel, Rommel's days were numbered.
British shipyards, obsolete and fraught with labor problems and poor management, were able to turn out only 1.3 million gross tons against losses of 7.8 million tons. The only saving grace in this battle of attrition was U.S. assembly-line construction of 7 million tons in 1942, growing to 13.6 million tons in 1943.
Germany, too, was constructing U-Boats on assembly lines. Sections were fabricated far from the shipyards, and transported there by canal on barges, welded together, fitted out and launched. By these methods 17 new U-Boats per month went down the ways in 1942.
Adm. Robert A Theobald was sent with a force of cruisers and destroyers to protect the northern flank of the main force; he did not believe the intelligence reports, convinced the Japanese would invade Dutch Harbor. The main thrust of the Japanese was, of course, Midway.
Admiral Chuichi Nagamo had just ordered his carrier planes armed with incendiary and fragmentation bombs for land operations, when suddenly reports of enemy ships nearing his force were received. He elected to re-arm his planes with torpedoes. But those planes couldn't be launched until the arriving flight from the bombing attack had landed. With the returning planes on deck and the torpedo planes not yet launched, the Americans fell on his task force. Four Japanese carriers were lost, and Japan went from the offensive to defensive, the turning point of the War in the Pacific. Theobald missed the action entirely.
The Japanese had planned to change their codes in April, but delayed until after the Midway attack. Had they changed their codes as planned the Americans would have not been able to read their intentions. Three Japanese carriers and a heavy cruiser were sunk, the heaviest loss to their fleet since the war began.
In 1941 the Allies had lost 429 ships totaling 2 million tons to U-Boats, while sinking 35 submarines. In 1942 six million tons and 1155 ships fell prey to the "gray wolves," although 87 U-Boats were sunk. Dönitz had 91 operational U-Boats in January, 1942, but by year's end the number rose to 212.
At the start of 1943 the Battle of the Atlantic was still in doubt. Scientists on both sides were rapidly developing new weapons and countermeasures.
Alarming intelligence reports were filtering out of Germany which mentioned new secret weapons - long-range rockets, jet airplanes, and explosives of unimaginable power which were said to tap the power of the atom.
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