Austro-Hungarian Navy submarines were also known as U-boats. U-boats are most known for their unrestricted submarine warfare in both world wars , trying to disrupt merchant traffic towards the UK and force the UK out of the war. In World War I , Germany intermittently waged unrestricted submarine warfare against the UK : a first campaign in was abandoned after strong protests from the US but in the Germans, facing deadlock on the continent, saw no other option than to resume the campaign in February The renewed campaign failed to achieve its goal mainly because of the introduction of convoys.
Instead the campaign ensured final defeat as the campaign was a contributing factor to the entry of the US in the First World War. This ultimately came to a head in May , known as Black May , in which U-boat losses began to outpace their effect on shipping. The first submarine built in Germany, the three-man Brandtaucher , sank to the bottom of Kiel Harbor on 1 February during a test dive.
Dredging operations in rediscovered Brandtaucher ; she was later raised and put on historical display in Germany. At the beginning of the century, the German commander of the Navy Alfred von Tirpitz was building the High Seas Fleet with which he intended to challenge the supremacy of the Royal Navy. He focused on expensive battleships and there was no role for submarines in his fleet. Because speed and range were severely limited underwater while running on battery power, U-boats were required to spend most of their time surfaced, running on fuel engines, diving only when attacked or for torpedo strikes.
The more ship-like hull design reflects the fact that these were primarily surface vessels that could submerge when necessary. This contrasts with the cylindrical profile of modern nuclear submarines , which are more hydrodynamic under water where they spend the majority of their time , but less stable on the surface.
While U-boats were faster on the surface than submerged, the opposite is generally true of modern submarines. Between and fourteen big boats with four torpedo tubes and two reload torpedoes were ordered. These boats used a kerosene engine which was safer than gasoline and more powerful than steam , but the white exhaust of the kerosene betrayed the presence of the U-boats, robbing them of their primary asset, their stealth.
