The birth of the Ottoman state is shrouded in legend. Whatever the truth of its origins, the Ottoman's formed an Empire which almost succeeded in bringing Christian Europe to its knees. During the last decades of the 13th century, the ambitious Osman Bey's tiny mountain state took eight frontier castles plus the Turkish town of Eskisehir. In 1299 Osman seized Yenisehir after working up the Kara Su valley. With this as its first real capital, the Ottoman state emerged into history poised above the fertile shores of the Sea of Marmara.