Submarine warfare in the Black Sea campaigns (1944)
Submarine warfare in the Black Sea in World War II during 1944 involved engagements between submarines of the Soviet Black Sea Fleet attacking Axis merchantmen, defended by Romanian and German naval warships, as well as German U-boats and Romanian submarines attacking Soviet merchants on the eastern Black Sea. Before the conclusion of the campaign, Romania joined the Allies after King Michael's Coup. These engagements were a part of the naval Black Sea campaigns. Background. As during the first 1941 campaign, the 1942 campaign and the 1943 campaign, the Soviet Navy  sent submarines against the Axis supply lines along the western coast of the Black Sea: at the beginning of the year however the Soviet Navy possessed only 16 operative submarines. German U-boats of the 30th U-boat Flotilla operated on the eastern sites of Black Sea, attacking Soviet targets. The Romanian Navy employed the newly built submarines NMS Marsuinul and NMS Rechinul but without scoring success. It also inherited five CB-class midget submarines left by Italy, however only two of them were operable by July 1944 and were not used in offensive action. Outcome. The German anti-submarine  capabilities in 1944 effectively neutralized the threat of Soviet submarines in the Black Sea. On the other hand, a combination of heavy Soviet anti-submarine actions prevented the 2 newly built Romanian submarines to achieve successes, while the 30th U-boat Flotilla was effectively eliminated by the combined effect of an air raid on Costanta on 20 August and the following King Michael's Coup (negating the survived U-boats a safe harbor and forcing their scuttling).