Battle of the Bosporus

The Battle of the Bosporus was a naval engagement during World War I on 10 May 1915 between the Russian Black Sea Fleet and the German battlecruiser Goeben (formally the Ottoman Yavuz Sultan Selim) in the Black Sea, north of the Bosporus, resulting in a tactical victory for the Russians. The battle took place during the main operation of the Black Sea Fleet aimed at shelling the Bosporus fortifications. The action of the Goeben led to the interruption of the operation, but it did not manage to inflict significant damage to the Russian fleet, suffering only minor damage itself.

Background
After the outbreak of hostilities between Russia and the Ottoman Empire on 29 October 1914, naval operations in the Black Sea primarily involved shelling coastal targets and laying mines. The core of the Russian fleet in this area consisted of five outdated battleships of the pre-dreadnought generation, each armed with four 305 mm guns, except for the weaker Rostislav with 254 mm guns. The main adversary of the Russian Black Sea Fleet was the German battlecruiser Goeben, which, after breaking through to Constantinople along with the cruiser Breslau, was formally incorporated into the Ottoman navy as Yavuz Sultan Selim, although it was still known in practice by its original name. It significantly surpassed each of the Russian ships existing at the beginning of the war in terms of speed, armor, and artillery, which included 10 guns of 28 cm caliber, with a higher rate of fire than the Russian heavy guns. This forced the Russians to operate in groups consisting of at least three battleships to equalize the odds in artillery combat. Additionally, due to the older construction of the Russian battleships, each hit could have serious consequences for them, especially in long-range duels, when steeply falling shells could penetrate the deck. The first inconclusive battle between the Black Sea Fleet and the Goeben occurred on 18 November 1914, near Cape Sarych, in which both sides' ships suffered damage.

Parallel to the start of the Dardanelles Campaign by the Western Entente powers, the Russian command ordered demonstrative actions to divert the attention of the Ottomans, including shelling positions and a possible local landing in the Bosporus area. To this end, on 28 March, 25 April, 2 May, and 3 May 1915, the Black Sea Fleet shelled Ottoman fortifications north of the Bosporus, also using seaplanes carried by base ships in the action. However, these actions did not lead to significant damage. On May 6, Russian ships returned to the base in Sevastopol after the final raid, during which 10 Ottoman ships (including 4 steamers) were sunk, seriously disrupting Ottoman coal transport, and an Italian ship carrying contraband was seized. On the same day (May 6), the best ships available to the Ottomans were sent on a raid into the Black Sea: Goeben and the cruisers Midilli and Hamidiye. On the morning of May 8, Goeben sailed along the coast of Crimea, but there were no encounters with the Russian fleet or shipping, nor was there any shelling of the coast due to limited ammunition supplies. The Ottoman ships then returned to port by evening.

Around noon on May 8, the main Russian ships left Sevastopol but encountered no enemy. Therefore, the main forces of the Black Sea Fleet set out in the afternoon for another operation to shell Ottoman positions and raid with light forces in the Ottoman coal basin around Zonguldak. The Russian squadron consisted of 5 battleships, 2 protected cruisers, an unarmored aircraft cruiser (Almaz), 15 destroyers (7 of them modern, with turbine propulsion), 6 naval trawlers (converted steamships), and the seaplane carrier Imperator Aleksandr I with 5 seaplanes (3 Curtiss and 2 M-5).

In the morning of May 9, the cruiser Kagul and the destroyer Biespokojnyj conducted reconnaissance in the area of Zonguldak – Kozel, damaging two Ottoman ships, while the cruiser Pamiat' Mierkurija and the destroyer Dierzkij shelled the port of Ereğli, causing fires and sinking one ship. The Russians also attempted to land a sabotage group from a motorboat towed by a boat to cause damage in the port, but they had to retreat (without casualties) due to rifle fire.

After receiving reports of the shelling of Ereğli, the battleship Goeben was ordered to take action against the Russian group and left the Bosporus in the afternoon. However, by that time, the Russian ships had already left Ereğli. At 2:38 P.M., Goeben spotted the Russian submarine Tiulen on the surface and turned back, pretending to return towards the Bosporus, causing the submarine to not report the presence of the battleship. Before entering the strait, Goeben headed east, remaining in the Black Sea to locate the Russian main forces the next day and, if possible, surprise them while they were separated.

Battle
On May 10, at dawn, the Russian ships were about 22 miles from the Bosporus. The bombardment group consisted of the older battleship Tri Sviateitelia (under the command flag of Rear Admiral N. Putiatin, commander of the 2nd Brigade of Line Ships) and the newer Pantelimon, which replaced the weaker Rostislav due to its longer-range guns. At 5:40 A.M., the group headed towards the shore, following the minesweepers tasked with clearing the minefields, escorted by six older destroyers from the 4th and 5th Destroyer Divisions, which were also towing minesweeping gear, and two newer destroyers from the 1st Destroyer Division. The battleships Evstafi, Ioann Zlatoust, and Rostislav, along with the remaining destroyers, formed a covering group, protecting the bombardment group from the seaward side. The cruisers Kagul and Pamiat' Merkuria were sent to watch to the west and east, respectively; the latter sank a small Ottoman sailing ship carrying coal. A Curtiss seaplane was also launched into the air.

At 5:40 A.M., the Russian fleet was spotted by the Ottoman destroyer Nümune-i Hamiyet, which was on patrol near the Bosporus, and it reported the presence of the Russian fleet via radio. The destroyer later approached closer as the Russian group was already turning, and at 7:10 A.M., it fired on the minesweepers from a distance of 4.1 nautical miles. It was fired upon ineffectively by the battleship Pantelimon, after which it withdrew. Pantelimon also fired seven shots at a larger ship observed deeper in the strait (identified as a Turgut Reis-class battleship).

Approaching from the east at high speed, Goeben was detected before 7:00 A.M. by the vigilant cruiser Pamiat' Merkuria and a seaplane, which alerted the main forces. The Russian cruiser returned to the group at maximum speed to evade the faster Goeben. Upon receiving information about the opponent, the main Russian commander, Admiral Eberhardt, directed the battleships of the covering force to the south to approach the bombardment group. Simultaneously, orders to return were given for the detached battleships, which had already moved about 15 nautical miles away. The reversal of the bombardment group on the opposite course took 18 minutes due to the need to turn in the narrow, mine-swept channel. At 7:41 A.M., upon reaching the shallower waters where mine barriers could be present, the battleships of the main force turned north again, with the enemy approaching from the starboard side at a distance of about 15 nautical miles. Due to the surprise of the divided Russian forces, the Germans had a potential opportunity to achieve victory, even over the entire Russian squadron.

The battleships Evstafi, Ioann Zlatoust, and Rostislav engaged in battle in line-ahead formation, while Goeben changed course to parallel them, sailing on their starboard side. At 7:51 A.M., Ioann Zlatoust and Goeben opened fire on each other from a distance of 9.4 nautical miles, followed by the flagship battleship Evstafi. According to procedures developed in the fleet, Ioann Zlatoust directed the centralized fire of both battleships. Both groups exchanged fire, but initially without effect. Subsequent five-gun salvos began to surround the flagship Evstafi, flooding the rangefinders with water spouts and damaging the splinter shields and wooden elements, although no direct hits were achieved. Initially, the Russian salvos were too short, but the water spouts they caused somewhat hindered the Germans' aim. Rostislav (commanded by Captain of 1st Rank Kazimierz Porębski) did not participate in the bombardment to avoid interfering with the correction of fire for the 305mm guns of the stronger battleships. The commander of the Russian group and the entire Black Sea Fleet, Admiral Andrei Eberhardtt, skillfully maneuvered, making course and speed adjustments to make it difficult for the enemy to target. In particular, instead of increasing the speed of the column after the Germans obtained cover, he reduced it from 10 to 9 knots, causing the next salvo to fall short of Evstafi. He also facilitated the approach of the remaining battleships.

During the battle, around 8:05 A.M., the Russian squadron was joined by the battleships Tri Sviatitelia and Panteleimon, sailing at maximum speed (Panteleimon even surpassed the flagship of the 2nd Brigade, reaching a speed of 17.5 knots at the end of the maneuver – faster than during trials). As Panteleimon caught up with the rear Rostislav, it independently opened fire with its 305 mm guns and achieved a hit with the second salvo fired at close to maximum effective range, about 10.4 nautical miles away, at 8:13 A.M. The shell hit the left side of Goeben amidships, below the waterline, tearing apart at the lower edge of the armor belt. This caused localized flooding of a bulkhead corridor (without affecting the speed of the battlecruiser) and disabling one of the 15 cm guns. In the next few minutes, Panteleimon, followed by Tri Sviatitelia, took their positions ahead of the retreating Rostislav in the line of battle. Admiral Eberhardt then ordered a slight turn to the right, trying to reduce the distance, and the engagement distance decreased to 7.3 nautical miles. Russian destroyers remained on the left side of the battleships, ready for a potential torpedo attack. Goeben was hit by two more shells, in the bow and in the torpedo net compartment, which hung overboard. These shells also did not cause significant damage, but at 8:16 A.M., Goeben broke off the engagement and turned to the right. The German commander, attempting to draw the Russians away from the Bosporus, headed north, maintaining a distance of 12–13 nautical miles. The Russian battleship squadron pursued Goeben for several more hours, hoping that the damage would reduce its speed. Eventually, however, Goeben, after turning eastward, accelerated and easily escaped from its pursuers, disappearing from sight around 3 P.M.

Aftermath
To support Goeben, upon sighting the Russian fleet near the Bosporus, the commander of the Ottoman fleet – German Rear Admiral Wilhelm Souchon – ordered steam to be raised and also sent out the cruiser Midilli. However, Midilli only managed to arrive at the scene around noon, after the Russians had departed. To protect the returning cruisers from potential submarines from the Bosporus, the Ottoman torpedo cruiser Peyk-i Şevket and the destroyer Yadigar-i Millet were also sent out. However, these units did not encounter any enemy vessels, as Tiulen left patrol due to engine problems, and Nierpa, sent as a replacement, did not arrive in time.

The Russian admiral considered sending the minesweepers back to base and returning with the main force to the Bosporus, but a nocturnal storm caused the entire fleet to return to Sevastopol on May 11th.

The German-Ottoman side interrupted the Russian operation to shell the Bosporus fortifications, but despite the favorable tactical situation, they failed to inflict any damage on the enemy fleet. The command of the Russian squadron and its maneuvering by Admiral Eberhardt, which led to the effective combination of striking forces and hindered the German gunners' targeting, are highly praised. Although the Germans did not achieve any hits with 126 fired 28 cm caliber shells, their fire was initially assessed by the Russians as accurate, well-focused, and skillfully conducted. Despite the tactical victory, some criticism arose due to the limited effectiveness of the Russian shelling, considering the number of shells fired. Evstafi fired 60 rounds of 305 mm and 32 rounds of 203 mm, Ioann Zlatoust fired 75 rounds of 305 mm and 4 rounds of 203 mm, Panteleimon fired 16 rounds of 305 mm, and Tri Sviatitelia fired 13 rounds of 305 mm (a total of 164 rounds of the main caliber and 36 rounds of 203 mm caliber – approximately 1.5% hits). The application of centralized fire control techniques in practice did not meet expectations. The decision to significantly separate the bombardment group from the covering group was also criticized, as it posed a risk of destruction to either group, which did not occur due to the fortunate course of the battle and skillful further command. Despite this, the fleet's actions were deemed a success, and some Russian officers and sailors – especially those from the battleship Pantaleimon – received decorations.

The battle of the Bosporus was one of the two largest naval engagements in the Black Sea during World War I, alongside the Battle of Cape Sarych, involving the main forces of both sides, although no ships were sunk as a result.

Units of both sides
(F) – flagships


 * 1) – damaged units

Russian Empire

 * Main forces of the Black Sea Fleet – Admiral Andrei Eberhardtt
 * Battleship Division – Vice Admiral P. Nowickij:
 * 1st Battleship Brigade (escort group):
 * Evstafi (F/Admiral A. Eberhardt) – Captain 1st Rank (Commander) M. Fiodorowicz,
 * Ioann Zlatoust (F/Vice Admiral P. Nowickij) – Captain 1st Rank F. Winter,
 * Rostislav – Captain 1st Rank Kazimierz Porębski
 * 2nd Battleship Brigade (bombardment group) – Rear Admiral N. Putiatin:
 * Tri Sviateitelia (F) – Captain 1st Rank W. Łukin,
 * Panteleimon – Captain 1st Rank Mitrofan Kas’kow
 * Cruisers: Kagul – Captain 1st Rank S. Pogulajew, Pamiat' Mierkurija – Captain 1st Rank M. Ostrogradskij, Almaz
 * 1st Destroyer Squadron – Captain 1st Rank W. Trubieckij:
 * Dierzkij (F) – Commander 2nd Rank A. Gadd, Biespokojnyj – Commander S. Bierch, Gniewnyj – Commander W. Czerkasow, Pronzitielnyj – Commander W. Borsuk
 * 2nd Destroyer Squadron (Captain 1st Rank A. Zarudnyj):
 * Gromkij (F) – Commander F. Stark, Sczastliwyj – Commander F. Klimow, Bystryj – Commander B. Bykow
 * 4th Destroyer Squadron – Commander I. Podjapolskij:
 * Lejtnant Puszczin (F) – Commander W. Gołowizin, Zutkij – Commander A. Tichmieniew, Zywuczij – Senior Lieutenant (Lieutenant Commander) J. Tumanow, Zarkij – Lieutenant W. Sobieckij
 * 5th Destroyer Squadron – Commander A. Gieziechus:
 * Zwonkij (F) – Commander A. Gieziechus, Zorkij – Senior Lieutenant W. Pysznow, Zawietnyj – Commander W. Bubnow, Zawidnyj – Lieutenant P. von Stilberg
 * Sea mine party – Commander I. Engelman:
 * Minesweepers Witjaz (F), Rossija, St. Nikolai,
 * Minelayers/minesweepers Wielikaja kniaginia Ksenia, Wielikij kniaz Konstantin, Wielikij kniaz Aleksiej 
 * Seaplane carrier (auxiliary cruiser) Impierator Aleksandr I – Captain 1st Rank P. Giering
 * Submarine Tiulen – Senior Lieutenant P. Baczmanow

Ottoman Empire / Germany

 * Battlecruiser Yavuz Sultan Selim (formerly Goeben) – Kapitän zur See (Commander) Richard Ackermann
 * Destroyer Nümune-i Hamiyet – kidemli yüzbaşi Nezir Abdullah