The objective age to promote a naval blockade against England. As ' ' wolves in return of its presa' ' , thus they had been known the U-boats, that had rightened the British first-minister. England had a damage of 3,5 a thousand tons. But nor of glory the submarines only lived, therefore frequently they were destroyed by the reached enemies when being with depth bombs, or even though they disappeared without leaving tracks. They not only attacked ships, as well as ports, hydroelectric plants and any type of suspicious target. Now the U-boats did not act alone as in the First War, but now in set to have greater victory possibility.
Exactly far ones of the others the radio was an indispensable instrument for the communication with excessively. This battle did not only happen in air, but also in the sea, where to the English they had had many losses since the beginning of the war, when the submarines German invested in attack to its ships bringing terror even though the first civil population to be attacked when the merchant ship Athenia was torpedeado and sank, this event was what Germany lacked Great-Britain to declare war to it. Acuada for the U-boats, British Real navy was seen obliged to create a school in Liverpool for members of the crew of escort boats. The idealizer of this training was admiral Max Horton. It was pioneering, when suggesting that the ships if organized in convoys, surrounded for ships sentries to prevent afundamentos. Beyond submarines the Germans had used privateer ships with powerful weapons of war on board to make it difficult the maritime commerce of the enemy, as well as the transport of warlike material for the countries Allies. After the conquest of France in 1940, the French Atlantic coast served of base submarine to supply without needing to skirt the North Atlantic, thus diminishing distances that had later made the difference.