SMS Undine was the last member of the ten-ship Gazelle class of light cruisers that were built for the German Kaiserliche Marine (Imperial Navy) in the late 1890s and early 1900s. The Gazelle class was the culmination of earlier unprotected cruiser and aviso designs, combining the best aspects of both types in what became the progenitor of all future light cruisers of the Imperial fleet. Built to be able to serve with the main German fleet and as a colonial cruiser, she was armed with a battery of ten 10.5 cm (4.1 in) guns and a top speed of 21.5 knots (39.8 km/h; 24.7 mph). Undine was a modified version of the basic Gazelle design, with improved armor and additional coal storage for a longer cruising range. Undine was initially used as a artillery training ship for the gunners of the German fleet. She also took part in training maneuvers with other elements of the fleet, and during one of these exercises in November 1904, she accidentally rammed and sank the torpedo boat SMS S126. The ship remained in German waters, making only a single visit to a foreign port in 1909. Undine remained in service through mid-1912. During this period, in addition to her training duties, she served as an auxiliary icebreaker. After the outbreak of World War in August 1914, Undine was deployed to the Baltic Sea, serving in the Coastal Defense Division. She was tasked with patrolling the western Baltic and she also participated in offensive operations against Russian forces. She was attacked by the British submarine HMS E19 on 7 November 1915 and was hit by two torpedoes, the second of which detonated the ship's ammunition magazines. Undine exploded and sank, but casualties were relatively light, with fourteen or twenty-five killed in the sinking.