[3] When World War I began in 1914, the U-1 was deemed obsolete and was used only for training until 19 February 1919, when it was struck by another vessel while on an exercise.

The SM U-1 was a redesigned Karp class submarine by Austrian born engineer Raimundo Lorenzo de Equevilley Montjustín [de][4] working for the German shipbuilding company Friedrich Krupp Germaniawerft.

The main improvements over the export Karp class included trim tanks instead of a moveable weight, a redesigned forecastle to improve seagoing ability, a 10 cm (3.9 in) larger diameter and strengthened pressure hull which prevented oil leakage from the external tanks, a rearrangement of the internal equipment and a heavier ballast keel.

The Imperial German Navy avoided the use of gasoline due to the perceived risk of fires and explosions that had caused many accidents in early submarines, and instead of the gasoline engines that had powered the Karp boats, U-1 was given much safer Körting kerosene engines.

[5][1] After suffering damage from a collision while on a training exercise in 1919, U-1 was sold to the Germaniawerft foundation at the Deutsches Museum in Munich where it was restored and can be viewed on display.