The Ottoman fleet had performed abysmally in the Greco-Turkish War of 1897, forcing the Ottoman government to begin a drastic overhaul. Older ships were retired and newer ones acquired, chiefly from France and Germany. In addition, in 1908 the Ottomans called in a British naval mission to update their training and doctrine. In the event, the British mission, headed by Admiral Sir Douglas Gamble, would find its task almost impossible. To a large extent this was due to the political upheaval in the aftermath of the Young Turk Revolution; between 1908 and 1911, the office of Navy Minister changed hands nine times. Inter-departmental infighting and the entrenched interests of the bloated and over-aged officer corps, many of whom occupied their positions as a quasi-sinecure, further obstructed drastic reform. In addition, British attempts to control the Navy's construction programme were met with suspicion by the Ottoman ministers, and funds for Gamble's ambitious plans for new ships were not available. To counter the Greek acquisition of the Georgios Averof, the Ottomans initially tried to buy the new German armoured cruiser SMS Blücher or the battlecruiser SMS Moltke. Not able to afford the ships' high cost, the Ottomans acquired two old Brandenburg-class pre-dreadnought battleships, which became Barbaros Hayreddin and Turgut Reis. Along with the cruisers Hamidiye and Mecidiye, these two ships were to form the relatively modern core of the Ottoman battlefleet. By the summer of 1912, however, they were already in poor condition due to chronic neglect: the rangefinders and ammunition hoists had been removed, the telephones were not working, the pumps were corroded, and most of the watertight doors could no longer be closed.
Question: Which ships were the core of the Ottoman battlefleet?
Answer: Barbaros Hayreddin | Turgut Reis