speedy light cruiser , both under the command of the skilled German Admiral Wilhelm Souchon. Goeben was a modern design, and with her well-drilled crew, could easily outfight or outrun any single ship in the Russian fleet. However, even though the opposing Russian battleships were slower, they were often able to amass in superior numbers to outgun Goeben, forcing her to flee. A continual series of cat and mouse operations ensued for the first two years with both sides' admirals trying to capitalize on their particular tactical strengths in a surprise ambush. Numerous battles between the fleets were fought in the initial years, and Goeben and Russian units were damaged on several occasions. The Russian Black Sea fleet was mainly used to support General Nikolai Yudenich in his Caucasus Campaign. However, the appearance of Goeben could dramatically change the situation, so all activities, even shore bombardment, had to be conducted by almost the entire Russian Black Sea Fleet, since a smaller force could fall victim to Goebens speed and guns. However, by 1916, this situation had swung in the Russians' favor – Goeben had been in constant service for the past two years. Due to a lack of facilities, the ship was not able to enter refit and began to suffer chronic engine breakdowns. Meanwhile, the Russian Navy had received the modern dreadnought which although slower, would be able to stand up to and outfight Goeben. Although the two ships skirmished briefly, neither managed to capitalize on their tactical advantage and the battle ended with Goeben fleeing and Imperatritsa Mariya gamely trying to pursue. However, the Russian ship's arrival severely curtailed Goebens activities and so by this time, the Russian fleet had nearly complete control of the sea, exacerbated by the addition of another dreadnought, . German and Turkish light forces, however, continued to raid and harass Russian shipping until the end of the war in the east. After Admiral Kolchak took command in August 1916, he planned to invigorate the Russian Black Seas Fleet with a series of aggressive actions. 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, Bulgaria, were also mined. The greatest loss suffered by the Russian Black Sea fleet was the destruction of Imperatritsa Mariya, which blew up in port on October 20 (October 7 o.s.) 1916,