To complete the tragedy of the day, Bayezid, on hearing of the death of his father, and his own consequent accession to the throne, gave immediate orders for the murder of his brother Yacoub, who had been his valiant companion in arms in so many battles. This was effected in the presence of the dead body of the father. The brutal deed was justified by a verse from the Koran, “Rebellion is worse than execution.” It was assumed by Bayezid that his brother would claim the throne against him. This was the first recorded case of fratricide in the Othman royal race. Thenceforth it became the settled practice for a Sultan of Turkey, on his accession to the throne, immediately to put to death his brothers and other collaterals, lest they should dispute the succession with him. By the law of succession the eldest living male of the reigning family, and not the eldest son of a defunct Sultan, was entitled to the throne. This supplied an additional motive for the practice of fratricide, for the new Sultan, by murdering his brothers and uncles, ensured the succession, after his own death, to his eldest son free from competition. In later times, however, when public opinion would no longer justify fratricide, and when the law of succession of the oldest male in the family was more fully recognized, the Sultan, on his accession to the throne, directed the close confinement of his next heir, generally his brother. It followed from this practice that the heir to the throne, instead of being employed on State affairs, or as a general, and gaining experience, was treated as a prisoner, and was forbidden to take any part in public affairs. It will be seen that this practice of forced seclusion of the heir to the throne during the lifetime of the reigning Sultan was one of the main causes of the degeneracy of the Othman dynasty. Reverting to Murad, it has been shown how important an epoch his reign was in the growth of the Ottoman Empire. During the twenty-four years of war, in which he led his armies in the field, he never met with a reverse. He extended the Empire for the first time into vast territories inhabited not by Turks or by Byzantines, but by sturdy Christian races, such as the Bulgarians, Serbians, and Bosnians. For the first time also the Turks came into conflict with the Hungarians, and defeated them. The influence of the Empire was extended practically to the Danube. Some of the intervening territory was not treated as conquered country and added to the Empire, but was allowed to retain the position of tributary or vassal States, as in the case of Serbia. Other parts, such as Thrace, Macedonia, and Bulgaria, were fully incorporated in the dominion of the Sultan.