On August 4, 1941, a “sborno voyskovo yato” (composite squadron) was formed in Bulgaria, tasked with providing anti-submarine defense for naval convoys of Germany and its allied countries. These convoys navigated from Kyustendzha to the Bosphorus, a critical route for the Axis war effort in the region.
The unit consisted of two wings: the first, based at Balchik airfield, operated 5 Letov S-328 aircraft. The second wing, stationed in Sarafovo near Burgas, had 4 of the same machines. It is noteworthy that the Czech biplanes, better known by their nickname “Smolík”, received the designation “Vrana” (crow) in Bulgaria.
Specific tasks for the “yato” were received from the representative of the German Navy (Kriegsmarine) in Varna. Bulgarian command took the Kriegsmarine’s demands very seriously, leading to a significant reinforcement in mid-October when three more S-328s were added. This transformed the “yato” into a “sborno voyskovi orlyak” (regiment) with two “yato” of six aircraft each.
Anti-Submarine Missions and Tactics
Initially, the aviators had two primary objectives: to track Soviet submarines along convoy routes and to warn ships of their appearance. Additionally, they were to attack any enemy submarines detected within Bulgarian territorial waters with machine gun fire and bombs.
Later, these tasks expanded significantly. They included detecting mines and minefields at the entrances to Varna and Burgas ports, covering friendly ships during mine-laying operations, conducting rescue missions, and performing aerial reconnaissance, which was vital for military intelligence.
In the first months, a single aircraft armed only with machine guns continuously patrolled over convoys, while several standby machines remained on the ground with two to six 20-kg bombs suspended. Upon enemy detection, the patrol aircraft’s crew signaled the convoy and standby aircraft, simultaneously attacking the submarine with machine gun fire. However, the effectiveness of this tactic proved very low, so “Vranas” began patrolling with bombs. For safety, unused bombs were dropped before landing.
Key Engagements of 1941
In 1941, 5 instances of combat contact between Bulgarian aircraft and Soviet submarines were documented. On August 16, at 13:45, a patrol crew escorting the Bulgarian vessel “Tsar Ferdinand” and the Romanian “Kavarna” detected a submarine between the mouth of the Kamchiya River and Cape Emine. They strafed it with machine guns, and a standby aircraft that arrived dropped 4 bombs. Later, three more aircraft dropped 8 bombs, though no signs of damage to the submarine were found. It is presumed that Shch-211, which had landed a group of illegal emigrants near the Kamchiya mouth, was the target.
On August 30, likely the same submarine attempted to attack an air-covered convoy near Cape Emine. The actions of the aircraft were identical to the first case, and the result was also similar, with no confirmed impact.
On September 21, an air patrol spotted a submarine attempting to attack a convoy of two Romanian transports and five Bulgarian escort ships en route Shabla-Varna. A standby S-328, along with one German and one Romanian aircraft, were called to the scene. However, the submarine managed to escape before their arrival.
On September 29, a “Vrana” crew escorted a convoy of three Italian tankers on the Varna-Burgas route. The aviators did not spot the submarine, and the explosion of a torpedo striking the stern of the tanker “Superga” came as a complete surprise. The vessel quickly sank. According to Soviet sources, this victory was achieved by Shch-211, commanded by Captain-Lieutenant Devyatko.
On October 15, one transport vessel, escorted by four Bulgarian combat units and with air cover, was moving along the Varna-Shabla route. At 10:55, a submarine heading towards the ships at periscope depth was detected from the aircraft. This time, the S-328 carried 6 bombs, two of which were dropped in the first attack. Aviators reported a hit on the submarine’s hull, after which it quickly dived. The crew dropped the remaining bombs. With almost 100% certainty, it can be stated that the M-58 was sunk in this manner, which, according to Soviet documents, disappeared in this area between October 18-21.
In total, from August 6 until the end of 1941, Bulgarian aircraft participated in 68 missions, 41 of which were for convoy protection, ensuring the escort of 73 transport vessels.
Historical Analysis and Discrepancies
The material by Bulgarian colleague Stefan Boshnakov is undoubtedly of interest, as it illuminates a previously practically unexplored aspect of the Soviet-Bulgarian military confrontation in the Great Patriotic War, according to author Sergey Bogatyrev. On one hand, Bulgaria was a non-belligerent ally of Germany with all the ensuing consequences (close economic ties, provision of military bases, etc.). On the other hand, Stalin, clearly dissatisfied with Bulgaria’s position, waged a real war against it, including submarine actions.
By August 10, 1941, the waters of this country hosted several combat positions for Black Sea Fleet submarines: No. 12 near Cape Kaliakra, No. 13 between Varna and Cape Emine, and No. 14 in the Tsarevo area (now Michurin). By October 11, the number of combat positions in Bulgarian waters increased to five, extending along the coast. Soviet submarines conducted reconnaissance, landed sabotage and reconnaissance groups, attacked vessels (including those of neutral countries like Turkey), and laid minefields in Bulgarian waters. A Bulgarian transport, the “Shipka,” was lost to one of these mines. Additionally, on September 9, the submarine L-4 sank the Bulgarian schooner “Uspekh” with artillery fire. The peak of activity in this undeclared war occurred between July and October 1941, after which Stalin left Bulgaria in peace until September 1944, as hopes for a Bulgarian proletarian and peasant uprising were not realized.
Regarding the factual material provided by the author, the M-58 departed Sevastopol on its sixth and final combat patrol on October 16, 1941, to combat position No. 11. According to the deployment map of Black Sea Fleet submarines for October 11, 1941, this position was located at the approaches to the Romanian naval base Constanta. “M” type submarines were not used at all off the Bulgarian coast (Shch, S, and L types were used there).
Romanian and German anti-submarine forces do not claim the sinking of M-58. With a high degree of probability, it can be asserted that it perished on the night of October 21 due to a mine from the “S11” or “S12” barrier. During the day, submarines conducted patrols at the approaches to Constanta and retreated further offshore at night to recharge batteries. It was there, on October 21, that a coastal hydroacoustic station recorded a strong explosion of an unidentified nature. In any case, the M-58 could not have been sunk by a Bulgarian aircraft on October 15.
So, whom did the Bulgarian aviators attack that day? At the time of the engagement, the submarine Shch-215 was in this position (No. 21). Judging by the fact that it completed its patrol and returned to base on October 19, the submarine suffered no serious damage. Its place in position was taken on October 21 at 23:00 by Shch-212. It should also be noted that the author greatly exaggerates the effectiveness of using 20-kg high-explosive bombs against submarines, as in 1941, German and Romanian aviation, using depth charges (two types: large “WBD” and small “WBF”) against Black Sea Fleet submarines, achieved no successes. Both still claim the sinking of three Soviet submarines that year.
In reality, in 1941, the Black Sea Fleet lost 8 submarines (one due to an accident near its own coasts), but none of them were destroyed by aviation. In Bulgarian waters, the following perished: S-34 on November 12 near Cape Emine due to a mine; Shch-211 on November 16 near Cape Shabler met the same fate; and Shch-204 on December 6 near Varna, sunk by Bulgarian patrol ships.