submarine and two Russian destroyers attacked a Turkish convoy of four transports escorted by a cruiser and two destroyers. The Russian ships sank all four transports without losing a ship. Later, during the summer of 1916, the Ottoman army, under, Vehip Pasha, was ordered to re-take Trebizond. The Ottoman forces tried to march along the coast in June but the Russian fleet was able to reduce the speed of their advance to a crawl using naval bombardment to harass marching troops and destroy their supply columns. Eventually the Ottoman army gave up and withdrew. After Admiral Kolchak took command (August 1916), the Russian fleet mined the exit from the Bosporus, preventing nearly all Ottoman ships from entering the Black Sea. Later that year, the naval approaches to Varna were also mined. The greatest loss suffered by the Russian Black Sea fleet was the destruction of the modern dreadnought , which blew up in port on 7 October 1916, just one year after it was commissioned. The sinking of Imperatritsa Mariya was never fully explained; it could have been sabotage or an accident. Revolution and Civil War The Revolution and subsequent civil war devastated the Russian Navy. Only the Baltic fleet based at Petrograd remained largely intact, although it was attacked by the British Royal Navy in 1919. Foreign Interventionists occupied the Pacific, Black Sea and Arctic coasts. Most of the surviving Black Sea Fleet warships, with crews loyal to the White Russian movement, became part of Wrangel's fleet under the control of commander Pyotr Nikolayevich Wrangel and after evacuating White forces and civilians from the Crimea were eventually interned in Bizerta, Tunisia. Russian sailors fought on both sides in the conflict. The sailors of the Baltic fleet rebelled against harsh treatment by the Soviet authorities in the Kronstadt rebellion of 1921. The surviving ships formed the core of the Soviet Navy on its 1918 establishment, though the remnants of Wrangel's fleet never returned to Russia. Ranks of the Imperial Navy (English translation) Beginning in the second half of the 19th century, ranks of the IRN were divided according to speciality and branch. Deck ranks and rates Seamen and NCO's Seaman First Seaman Quartermaster Seaman Petty Officer 3rd Class (Boatswain's mate, Third mate, Skipper's mate, Stuurman's mate) Petty Officer 2nd Class (Boatswain, Second mate, Schooner skipper) Petty Officer 1st Class (Unteroffizier) (Constable) Chief Petty Officer (Skipper) Senior Chief Petty Officer (Senior