Soviet M-class submarine

1930s to 1940s

Submarines of this class were in four series: VI, VI-bis, XII, XV. The number of VI and VI-bis series boats were almost equal. Series XII was a re-developed project with equivalent tactical characteristics. The first series were powered by one diesel engine and one electric motor. Series XV had developed separately with improved characteristics, including the main ballast in light hull and two shafts. These vessels were mainly used by the Black Sea Fleet and the Baltic Fleet.

Although the design was satisfactory, only limited results were obtained and losses were heavy with 33 submarines sunk between 1941 and 1945. M-103 disappeared in the Baltic Sea in mid-August 1941. The wreck was discovered in the late 1990s during a NATO minesweeping training exercise.^[1] Seven submarines were lost in the Black Sea, four depth-charged and sunk by Romanian warships (M-31 by the flotilla leader Mărășești,^[2] M-58 by the destroyer Regina Maria,^[3] M-59 by the destroyer Regele Ferdinand^[4] and M-118 by the Romanian gunboats Ghiculescu and Stihi^[5]) (both M-58 and M-59 however are also reported as lost on Romanian laid mines,^[6] while M-31 was also claimed by mines or a German vessel^[7] ) and three were sunk in minefields laid by the Romanian minelayers Amiral Murgescu, Dacia and Regele Carol I.^[8] By 1945, some 111 M-class submarines had been completed, with another 30 XV-series completed between 1945 and 1947.

Cold War

Two submarines of the early series of this class, along with two Soviet S-class submarines, (S-52 and S-53) and two Shchuka-class submarines (under lease, S-121 and S-123) were sold to the People's Republic of China in June 1954 as the foundation of the People's Liberation Army Navy Submarine Force. Both the M- and S-class submarines were sold to China, and two more M-XV series of this class (M-278 and M-279) were sold to China a few years later in 1956.Those purchased by China were renamed, but the two leased Shchuka-class submarines were not. The four M-class submarines bought by China were renamed National Defense # 21, 22, 23 (ex M-278) and 24 (ex M-279) respectively.^[9]

Modern times

An M-class submarine was discovered near Tallinn in May 2012. The submarine is located in Tallinn Bay between the islands of Aegna and Naissaar, at an approximate depth of 65 to 66 metres (213 to 217 ft). It is believed to be M-216, which was intentionally sunk in the area in 1962 for training purposes. Divers have confirmed that many components, including the periscope, are missing. It is also believed that the training exercise may have been ordered as a result of several deadly submarine accidents in the 1950s. One such accident happened near Paldiski, where the entire crew of M-200 died during a failed rescue operation.^[10]

In July 2015, another M-class (series XII) submarine was found in the Black Sea by divers off the Romanian coast at Costinești, at an approximate depth of 40 metres (130 ft).^[11][12] It is believed to be either M-34 or M-58, both being lost to Romanian minefields. The submarine is buried in sand up to the deck level and also completely filled with sand, making any further identification almost impossible. The upper part of the hull shows a pretty high level of damage - many ribs are exposed. The aft hatch was partially opened. The hull is in one piece, with the conning tower and deck gun intact.^{[citation needed]}

In April 2025, after a 20-year search, M-class submarine M-49 was found in the Peter the Great Gulf. M-49 had gone missing on 16 August 1941.^[13]