Battle of the Atlantic (1939-1945)

Context

The Traité of Versailles signed in 1919 ratifies the defeat of the Germany during the First World War. It cannot have but one defensive force any more: it is to him interdict to have an aviation, underwater and Porte-avions. The marine is limited to 108.000 tons, and no ship must measure more 10 000 tons.

Following the Treated of Washington of 1922 on the limitation of the naval armaments, the the United Kingdom and the the United States are limited to 525.000 tons for the Cuirassé S, the Japanese fleet of battleships must measure a maximum of 315 000 tons, the losers are the Italy and the France, limited each one to 175 000 tons.

After the come to power of Adolf Hitler, a bilateral naval agreement between the the United Kingdom and Germany are concluded in 1935. It stipulates that Germany can build 35% of the tonnage of surface and 45% of the underwater tonnage of the Royal Navy.

The Battle of the Atlantic

The first year

The Battle of the Atlantic begins as of September 1939. For the Franco-English ones, the blockade of the sea traffic takes part of a strategy of wear which must lead Germany to yield. At the same time as their ships control the seas, they carry out the damping of mines on strategic ways for Germany like the coasts of Norway. The Germans answer by a against-blockade where the underwater war plays a big role, as during the First World War. From June 1940, the Germans are Masters of the Atlantic coasts of the continent. Until 1943, the action of the U-boot against the allied boats crossing the Atlantic will be a showpiece of the German strategy to put Great Britain at knees.

In October, Günther Prien torpedoes and runs the battleship Royal Oak in the British naval base of Scapa Flow.

After having run a certain number of cargo liners, the German battleship of pocket Admiral Graf von Spee is damaged on December 13rd during the Bataille of Rio of Plata. It is scuttled in bay of Montevideo a few days afterwards.

The first period of happy times

June 1940 constitutes a new record for the Germany which destroys 585.000 tons of allied trading vessels.

In July, the U-Boote settle with Lorient for an direct access in the Atlantic. As of this month, Germany knows or go sympathies of the United States; president Roosevelt announcing that it will help England within the framework of neutrality. Nevertheless, to the entry in war of the United States, Germany will endeavor to avoid any provocation on sea by respecting the zone of American neutrality in particular covering the western half of the Atlantic Ocean.

This same month, the Royal Navy attacks the French fleet with the Bataille of Seas el Kebir, in order to avoid the delivery of the French fleet in the Nazi Germany by the Vichy government. The British ultimatum required of the ships flying French flag to go or pass to a port of a neutral country or to fight.

In October, Karl Dönitz installs the tactics of attack of the convoys in “packs” of U-Boote.

From February 1941, the the United States set up the fleet of the Atlantic. The next month, the more known Lend-Lease in French like the law “Lease-lend”, between into force. The escorts are organized and profited from the appearance of the Radar, it acts of the end of the first period of “happy times” of the U-Boote.

In April, the Germany destroys 688.000 tons of allied trading vessels. It is about a new record.

First reverses

In May 1941, the German battleship Bismarck runs the HMS Hood at the time of its first exit before sinking itself three days later approximately 650 km in the west of Brest.

From July, the British elements based in Iceland are raised by American troops. Destroyer S escort from now on the convoys on the totality of the course. All the ships of some nationality could integrate these convoys: the incidents were going to become inevitable. Thus, in October 1941, the destroyer Kearney would be torpedoed and the Reuben James would run with the near total of its crew.

In August, the decoding of Enigma will make it possible the Allies to include/understand the radio operator traffic of the U-Boote.

As from September the aerial cover of the convoys is improved.

The second period of happy times

The entry in war of the the United States following Pearl Harbor in December 1941 changes considerably gives it on the theater of operation of the Atlantic. British and Americans agreed to give priority to the destruction of Germany. It is only after they are turned over against Japan. The road of the North Atlantic must be held at all costs. The president Roosevelt imposes this priority on the navy and Mac-Arthur which wished to privilege the Pacific. For Dönitz, on the contrary, the road of the North Atlantic must be crossed even if it loses all its submarines there. A fight to the death begins.

The zone of operation of U-boote is extended to all the Atlantic Ocean, thus inaugurating a second happy period for the German submarines. In January 1942, the U-Boote make devastations along the American coasts. In spite of the rise out of arrow of the allied losses, the American navy does not set up the system of the convoys, preferring to use the forces surface to patrol along the roads of navigation. Not only one U-Boote will not be run by the Americans until in April, whereas in same time, more than 200 trading vessels will be cast.

In February, the addition of rotors on the machines Enigma of the Kriegsmarine has as a consequence the interruption of the decoding of the radio operator traffic. Thus March constitutes a new record for the Germany with 834.000 tons of allied trading vessels cast.

However, Hitler will not benefit at bottom from its advantage, obliging the admiral Dönitz to preserve good number of submarines in Norway and at sea the Mediterranean.

Generalization of the convoys

In May 42, the Americans end up being solved to institute the system of the convoys in direction of England. U-boote are folded back then on other zones (Gulf of Mexico and Caribbean Sea) where the ships are not protected thus. This system will extend quickly to all Atlantic as of June. The forces of escort will be regularly made up of two destroyers and four corvettes. At this time the submarines will attack rather in the center of the Atlantic, at the place where the convoys will be able to profit from no air help.

In May begins the “Bataille from the St. Lawrence” in Canada opposing U Boot German and the Canadian royal Marine and Alliés in the Golfe of the St. Lawrence, important zone of transit and starting point of many convoys.

From the month of June 1942, the Radar equipping a growing number of Destroyer S makes it possible to detect the submarines at long distance. Certain ships are also equipped with the H.F.D.F. ( High Frequency Direction Finder ), a radiogoniometer which can know the position of a submarine at the time when it transmits messages on short waves. The submarines are now located at the time of an attack and pitilessly pursued.

In October 1942 takes place the resumption of the decoding of the German radio operator traffic. In spite of the losses, the Germany succeeds in destroying 800.000 tons of allied trading vessels in November 1942. It is about the best month of all the war for the U-Boote.

In January 1943, Dönitz is named with the head of the Kriegsmarine. The underwater war becomes priority. In March the aerial cover becomes continuous for the convoys américano-British thanks to the use of four-engined planes Liberator with long operating range on departure of the England, the beginning of the participation of several Porte-avions in the Atlantic and on arrival of the centimetric Radar.

So the allied losses decrease by half in the northern Atlantique as of the next month. The tested techniques of formation of pack are balanced for the first time by a total failure for the Germans.

Attempts at German parades

The extent of the losses causes a fall of moral submariners. Much U-boote hesitates from now on to continue an attack. At the end of ego of May 43, Dönitz decides to withdraw all its submarines of the Atlantic northern. In July, the U-Boote run 97.000 tons in the Indian Ocean. From now on, the commercial tonnage launched by the allied building sites definitively exceeds the tonnage run by the Axe.

September 13rd, 1943, the admiral Dönitz again launches his submarines in the Atlantic. They have new equipment as the acoustic torpedo, a reinforced anti-aircraft armament and a detector radar. The acoustic torpedo, called breakage-destroyers, makes it possible U-boote to attack directly the ships of escort. It somewhat will shake moral Allies, but a parade quickly will be found by the presence of towed sound-effects men who will divert the torpedes of their objectives.

At the end of 1943, several U-boote are equipped with snorkel . This equipment makes it possible the building to remain in periscopic immersion while renewing its air.

In December, the German battleship Scharnhorst is run during the Bataille of the Northern Cape. It is about the last battle of surface of the Atlantic.

In November 1944, all the U-Boote are equipped with the Schnorchel, but have mitigated results. The German battleship Tirpitz is run by the British bombers.

In January 1945, the first standard submarine of XXIII is operational. But the the Baltic, mined by the Allied , is from now on impracticable for the German .

Assessment

(*) thousands of tons
(**) units

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