Image by Roman Grac from Pixabay 

Submarine

Submarines, which were developed in the 19th century and first used successfully in the American Civil War, fundamentally changed the character of naval special warfare. Capable of fighting the enemy both above and below the surface, they could either attack or interdict enemy shipping all over the world. At the beginning of the 20th century all navies gradually began to introduce this new type of weapon, even though capital ships were regarded as the most important means of gaining and defending naval supremacy.

Soon, however, greater ranges, increased speed, better armament with torpedoes and guns mounted on deck, and improved pressure hulls, which allowed greater depths, turned the submarine into a formidable weapon in the war at sea. World War 1 saw a breakthrough in the development of both strategy and tactics. Though often regarded as a negligible weapon of weak naval powers, the submarine displayed its capability as a most dangerous weapon against warship and merchant ship. The German High Seas Fleet, realizing that it had no chance of winning an open battle against the Grand Fleet, and in retaliation against Britain's distant blockade of German merchant ship, reverted to different forms of submarine warfare from late 1914 on wards. In 1917 a new offensive against Britain's lifelines inflicted severe losses upon Britain's trade and supply lines without, however, changing the course of the war.

During World War 2 the submarine again played an important role in german navy strategy. Based on World War 1 designs, these vessels infested all the world's oceans. They now attacked in groups ('wolf packs') in order to increase their effectiveness. In many ways Germany's submarine strategy proved the model of the naval strategy of other navies, which, like the US Navy in the Pacific War, also used submarines widely to interdict enemy shipping. But in spite of the heavy losses suffered by Allied shipping once again, the development of new countermeasures and the breaking of the German Enigma code helped to win the battle, which was mainly fought in the Atlantic Ocean.