Kastamuni, practically coterminous with the Roman province of Paphlagonia, stood between the Ottoman possessions and the Black Sea. In the campaign of 1393, Samsun and the cities of the interior between Samsun and Angora, were captured by the Osmanlis. When the Ottoman army advanced to attack Kastamuni, Bayezid offered to allow the emir to become his vassal, if he would surrender to him the emirs of Sarukhan and Menteshe. Whether the lesser Bayezid was unwilling to violate the laws of hospitality, or put little faith in the promises of the conqueror after the fate which had overtaken the emir of Aïdin, it is impossible to say. He and his guests fled to the court of Timur. The occupation of Sinope gave the Osmanlis an excellent port on the south coast of the Black Sea. Bayezid was now master of the greater part of Anatolia, but master only in name. He had not assimilated these conquests. As later events proved, the inhabitants of these territories were still loyal to their former rulers. IV After his return from the first Anatolian campaign, Bayezid ordered a general advance along the northern and north-western frontiers. One band invaded Bosnia, but did not make much headway. Three bands entered Hungary, and initiated the system of rapid raiding that in time reached as far as Germany, and made the ‘Turks’ the nightmare of Slavic, Teutonic, and Italian Europe. The first battle on Hungarian soil was fought at Nagy-Olosz, in Syrmia, not far from Karlovitz, where three centuries later the Osmanlis signed the death-warrant of their _Weltpolitik_. The Danube was crossed also near Silistria. Before the terrible akindjis could penetrate far into his country, the hospodar Mircea surrendered, or was made prisoner. After a short exile at Brusa, he regained his liberty by consenting to the payment of a tribute of three thousand ducats, thirty horses, and twenty falcons.[460] He agreed to help Bayezid against the Hungarians, who had long been asserting a sovereignty over Wallachia, and in return Bayezid promised to settle no Moslems and build no mosques north of the Danube. In the first Hungarian invasion, Bayezid received more valuable aid from the Wallachians than from his janissaries. There were no better fighters in the Balkan peninsula than these descendants of the soldiers of Trajan. The interference of Sigismund prevented an Ottoman invasion of Moldavia, whose hospodars remained altogether independent of the Osmanlis until the reign of Mohammed the Conqueror.[461]