The young man succeeded his father as the head of the tribe. He united in his character the traits of shepherd, freebooter, and warrior. Osman’s ambition was fired by a dream of conquest that seated him upon the Byzantine throne. He was upon the border of the decaying Greek empire to the west, and back of him were the vast, restless populations ready to enlist under any leader of strength and action. He invaded Nicomedia July 27, 1299, from which time his reign is usually dated. This was parallel with Edward I of England, Philip the Fair of France, and Andronicus Palæologus the elder of Constantinople. Slow encroachment was made upon the imperial domains of the Greek empire, while at the same time his authority was extended over considerable districts in the north and west of Asia Minor, including large parts of Phrygia, Galatia, and Bithynia. Prusa (Brusa) was captured and became the residence of Othman, and was the seat of his government when he died in 1326. Othman was succeeded by Orchan, his son, who extended the boundaries of the infant state with marked rapidity. He took Nicæa, the rest of Bithynia, the greater part of Mysia, and was the first Turkish ruler to pass over into Europe. He coined money in his own name, and assumed the prerogatives of royalty, and began the systematic organization of his government. A permanent military force was established. One of his strongest military organizations was composed of the children of conquered Christians who were reared in Islam, inured from their youth to the profession of arms. These became the famous Janissaries perpetuated in the conquests of the Turkish government until the middle of the nineteenth century. They were distinguished for their valor and fanaticism. Through more than three centuries, marked by a long series of great battles, they experienced only four signal reverses. One of these was by Tamerlane, in 1402, and another by the Hungarian general, John Huniades, in 1442. The present methods of administration of the Ottoman empire are due in no small measure to the despotic nature and fanatical character of the Janissaries. Their assumption finally reached such a state that it became necessary to extirpate them by the sword to prevent their exercise of authority over the sultans themselves. This was accomplished by Mohammed II in 1826.