The Hrabri class consisted of two submarines built for the Kingdom of Serbs, Croats and SlovenesYugoslavia from 1929 onby Vickers-Armstrong in the United Kingdom. Launched in 1927, the boats were named (Brave) and (Fearless). Their design was based on that of the British L-class submarine of World War I, and they were built using parts from L-class submarines that were never completed. The Hrabri-class were the first submarines to serve in the Royal Yugoslav Navy (KM), and after extensive sea trials and testing they sailed from the UK to the Adriatic coast of Yugoslavia, arriving in April 1928. They were armed with six bow-mounted torpedo tubes, two deck guns, one QF 2-pounder () L/39 anti-aircraft gun and two machine guns. Their maximum diving depth was restricted to by Yugoslav naval regulations.
Prior to World War II, both submarines participated in cruises to Mediterranean ports. In 1930, Nebojša was damaged in a collision with a merchant ship. In 1933–1934 both boats were refitted, their superstructure was extensively modified and the 2-pounder gun on each submarine was replaced with a single Hotchkiss M1929 anti-aircraft machine gun. By 1938 the class was considered to be obsolete, but efforts to replace the two old boats with modern German coastal submarines were stymied by the advent of World War II, and the class remained in service.
Immediately before the April 1941 German-led Axis invasion of Yugoslavia, the two boats conducted patrols in the Adriatic Sea. Hrabri was captured by the Italians at the time of the Yugoslav surrender in mid-April, and after an inspection she was scrapped. Nebojša evaded capture and made it to Egypt to join the British Royal Navy (RN). Along with other vessels and crews that had escaped during the invasion, Nebojša formed part of the KM-in-exile, which operated out of eastern Mediterranean ports under the operational command of the RN. Nebojša was overhauled and initially served with RN submarine forces in the Mediterranean Sea as an anti-submarine warfare training boat. At the end of 1941 the RN prohibited her from diving and she was employed as a battery charging station for other submarines. In May 1942 her crew were removed and placed in a British military camp following a revolt by Yugoslav generals based in Egypt, and she received an almost entirely RN crew. Nebojša underwent another extensive overhaul by the RN, then she was briefly utilised for training in Beirut. The boat was formally handed back to the KM-in-exile in mid-1943, after which she underwent a further substantial refit. Nebojša eventually made her way to Malta where the headquarters of the KM-in-exile was then located. After the war in Europe ended, Nebojša was transferred to the new Yugoslav Navy and renamed Tara. She was used in a static training role until 1954, when she was stricken.
Background
The naval policy of the Kingdom of Serbs, Croats and Slovenes (the Kingdom of Yugoslavia from 1929) lacked direction until the mid-1920s, although it was generally accepted by the armed forces 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. A few naval officers attended submarine warfare courses in the United Kingdom and France in the hope that funds might be forthcoming from the government to create a submarine arm for the navy. In 1925, King Alexander visited the navy for the first time and several senior naval officers suggested to him that a submarine arm was needed. In the middle of 1926, the submarine visited the Adriatic to familiarise Yugoslav naval officers with the class and undergo trials to demonstrate its capabilities. In the same year, a modest ten-year construction program was finally initiated to build up a force of submarines, coastal torpedo boats, torpedo bombers and conventional bomber aircraft for coastal defence. The two Hrabri-class submarines, named (Brave) and (Fearless), were some of the first new acquisitions aimed at developing a naval force capable of meeting this challenge. Nebojša was also named after the eponymous medieval tower near the Yugoslav capital of Belgrade, which had played a prominent part in battles between Serb and Ottoman Empire forces during the wars of Serbian independence from 1804 to 1817, and again during the Austro-Hungarian Empire campaigns against the Kingdom of Serbia in World War I.