Yugoslav naval policy in the interwar period lacked direction until the mid-1920s, although it was generally accepted that the Adriatic coastline was effectively a sea frontier that the naval arm was responsible for securing with the limited resources made available to it. In 1926, a modest ten-year construction program was initiated to build up a force of submarines, coastal torpedo boats, torpedo bombers and conventional bomber aircraft to perform this role. The Osvetnik-class submarines were one of the acquisitions aimed at developing a naval force capable of meeting this challenge. The Osvetnik-class was built for the Kingdom of Serbs, Croats and Slovenes by the Ateliers et Chantiers de la Loire company at Nantes, France. Their design was based on a partial double hull design developed by ACL's chief engineer, G. Simonot, which was similar to the French. Their Serbo-Croatian names of and translate as "Avenger" and "Daring" respectively. They had an overall length of, a beam of, and a surfaced draught of. Their surfaced displacement was, or submerged, and their crews consisted of 43 officers and enlisted men. They had an operational depth of. For surface running, the Osvetnik-class boats were powered by two MANdiesel engines which were rated at that drove two propeller shafts. When submerged, the propellers were driven by two Nancy electric motors generating. They could reach a top speed of on the surface, and on their electric motors when submerged. They were armed with six torpedo tubes, one gun, and one anti-aircraft gun. On the surface, the boats had a range of at, and at submerged.
Service history
Smeli was launched on 1 December 1928, and Osvetnik on 14 January 1929. They arrived in the Bay of Kotor on the southern Adriatic coast on 9 December 1929. In 1932, the British naval attaché reported that Yugoslav ships engaged in few exercises, manoeuvres or gunnery training due to reduced budgets.
''Osvetnik''
First of the class, Osvetnik was involved in a series of visits to Mediterranean ports during the interwar period. She was captured in port by the Italians during the German-led Axisinvasion of Yugoslavia. She was refitted and modernised before being commissioned by the Italians as Francesco Rismondo, but was only used for training and experimentation. After the Italian surrender, she was captured then scuttled by the Germans in September 1943.
''Smeli''
Smeli was the second and last of her class. She also participated in several cruises in the Mediterranean during the interwar period. After capture by the Italians, Smeli was refitted and modernised before being commissioned as Antonio Bajamonti, but was only used for training and experimentation. She was scuttled by the Italians in September 1943 at the time of the Italian surrender.
