The 'Raid on Constanţa' was a Soviet attack by Vitse Admiral Filipp S. Oktyabrsky’s Black Sea Fleet on the Romanian port of Constanţa (26 June 1941).

Undertaken shortly after the start of 'Barbarossa', in which Romania was allied with Germany and took part in the land operations along the north-western coast of the Black Sea, this resulted in the only encounter between major warships in the Black Sea during World War II. The attack was planned as a co-ordinated undertaking between the Black Sea Fleet’s ships and aircraft to split the attention of the defenders, but the bombers were late and therefore did not attack at the designated time.

Two Soviet destroyer leaders were ordered to bombard the port in the early morning, covered by a cruiser and a destroyer. They caused some damage, but were engaged by Axis coastal artillery and several Romanian ships. The two destroyer leaders were slightly damaged and withdrew under fire, steaming into a Romanian minefield. One of the destroyer leaders was sunk and the cruiser was damaged by the mines as they departed the area.

Several groups of bombers attacked the city later on the same day and during the following night, but caused no damage to their targets. Nine bombers were shot down by anti-aircraft fire and Axis fighters. The defeat caused the Soviets to be much more cautious in using their ships within range of Axis defences.

After Romania had joined the Tri-Partite Pact in November 1940, the Germans agreed to establish coastal artillery batteries to bolster Romania’s obsolete coastal defences: one of the new installations was the Tirpitz battery to the south of Constanţa, and this was armed with three 280-mm (11.02-in) guns dating from the period before World War I, and had a complement of 700 German naval personnel despite being under nominal Romanian control, as were all the Axis in Romania.

Forewarned by Adolf Hitler about the scheduled date for the 'Barbarossa' invasion of the USSR on 22 June, the Romanian minelayers Amiral Murgescu, Regele Carol I and Aurora between 16 and 19 June laid 1,000 mines between Cape Midia and Tuzla to protect Constanța.

On 22 June the Romanian air force launched attacks against Soviet airfields in Bessarabia, destroying 37 aircraft on the ground. In retaliation four Tupolev SB twin-engined fast bombers of the Black Sea Fleet’s 40^th Bomber Aviation Regiment and four Ilyushin DB-3 twin-engined bombers from the 2^nd Mine and Torpedo Aviation Regiment attacked Constanţa during the afternoon of the same day. The attack was unsuccessful, and two of the SB bombers failed to return. Three DB-3 bombers attacked Constanța during that night, but achieved no success and suffered no loss. After the failure of these initial air attacks, Oktyabrsky decided to launch a combined air and naval attack on Constanța as well as a seaborne assault on the Danube river delta.

Two 'Leningrad' class destroyer leaders, Moskva and Kharkov, covered by the heavy cruiser Voroshilov and the destroyers Soobrazitelny and Smyshleny, constituted the task force for the attack. The latter destroyer ran aground en route, however, and had to return to port. The Soviets also had the obsolescent battleship Parizhskaya Kommuna some 100 miles (160 km) offshore to exploit any initial success, and Soviet bombers were also to join the attack.

The task force approached and shelled Constanţa in the early hours of 26 June, setting fire to some oil tanks and warehouses as well as damaging some of the port’s infrastructure. The Romanians had expected a Soviet raid, however, and their defences, consisting of the destroyers Regina Maria and Mărăști as well as the Tirpitz battery had been readied to engage the Soviet ships. In the 10 minutes from 03.58, Moskva and Kharkov fired no less than 350 shells from their 130-mm (5.1-in) guns. The two Romanian warships opened fire with their 120-mm (4.7-in) guns at 04.12, hitting Kharkov eight minutes later. The Tirpitz battery also opened fire at 04.22. Moskva was also damaged by the Romanian warships, her mainmast being brought down by a 120-mm (4.7-in) shell, while Kharkov was further damaged by the fire of the Tirpitz battery. The surprised Soviets began to withdraw, but steamed into a Romanian minefield. Moskva struck a mine and sank, 268 men being killed and 69 men surviving to be taken prisoner by the Romanians. According to most sources, she was sunk by Romanian mines, although shells from Regina Maria and the Tirpitz battery, or otherwise an unintentional 'friendly fire' torpedo attack by Soviet submarine Shch-206 have also been suggested as causes. Voroshilov was also damaged by a mine that exploded when Soobrazitelny's paravanes triggered it.

Aircraft of the Aviatsiya Dal’nego Deystviya (Long-Range Aviation) and the Black Sea Fleet’s 63^rd Naval Aviation Brigade co-ordinated their attacks on targets in Bucharest, Sulina, Constanţa and the lower reaches of the Danube river on the morning of 26 June. Some 17 DB-3 bombers of the 21^st Long-Range Bomber Regiment took off from their airfield in Saky in Crimea. The anti-aircraft fire of the ships in Constanţa harbour was heavy, and at least one bomber deliberately dropped its bombs into the sea. The Soviet aircraft were intercepted by Axis fighters after bombing Constanţa and one bomber was shot down, although the bombers' gunners claimed to have shot down two fighters. The regiment lost seven aircraft during that morning to all causes, and an additional pair each returned home with one engine inoperative. After this, Aviatsiya Dal’nego Deystviya commanders decided that their bombers would fly over Romania only at night.

The 63^rd Naval Aviation Brigade’s operations were more closely integrated into the navy’s bombardment, and took the form of attacks on Constanţa in three waves. It was intended that the first would be delivered before the ships opened fire and the second during the bombardment, while the last was to distract the Axis forces as the Soviet ships withdrew. The pair of DB-3 twin-engined bombers from the 2^nd Mine and Torpedo Aviation Regiment that comprised the first wave had to return before reaching their target as a result of mechanical problems. Of the second wave’s two SB fast bombers, one returned because of a malfunction and the other failed to return. The third wave was intercepted by a squadron of Messerschmitt Bf 109 fighters of the III/Jagdgeschwader 52 well after Moskva had sunk, and these German fighters claimed to have shot down 11 DB-3 and seven SB bombers. Seven SB bombers managed to get through to attack Constanţa.

The Romanians claimed to have shot down nine SB bombers during the battle, two of them claimed by Amiral Murgescu and one by Mărăşti. The remaining six aircraft were shot down by a Romanian anti-aircraft battery of 102-mm (4-in) guns.

The failure of the raid, together with other losses suffered by the Black Sea Fleet, caused Oktyabrsky henceforward to be much more cautious in his use of surface warships.