Between these lands and Pomerania lay the savage Prussians. Among them Bishop Adalbert of Prague, the Apostle of Bohemia, had ended his life by martyrdom in 997: and subsequent efforts, whether of bold missionaries or of victorious Polish Kings, equally failed. At length in 1207 some Cistercian monks from Poland obtained leave from Innocent III to make another attempt on Prussia. They were well received, and Christian of Oliva was consecrated bishop. But the rulers of neighbouring lands, notably Conrad, Duke of Masovia, which lay just to the south, schemed to turn these converted Prussians into political dependents, and Christian welcomed their armies as a means of hastening on the nominal change of religion. A crusade was set on foot; but the natives resisted with success, and began to destroy the monasteries established in the country. Consequently, in 1226 Duke Conrad invited some members of the Teutonic Order to help him. In 1230 came a large number of the knights, and a devastating war which lasted for more than fifty years (1230-83), ended in the nominal conversion of the remaining inhabitants. During the war German colonists were placed upon the conquered lands and towns were founded--Königsberg (1256) in honour of Ottocar of Bohemia, who lent his aid for a time; Marienburg (1270), which became the headquarters of the Teutonic Order. Indeed, it was the Order which reaped the benefit of the conquest. In 1243 Innocent IV divided the country ecclesiastically into four bishoprics, which were placed afterwards under the Livonian Archbishop of Riga as their Metropolitan. One of these four--Ermland--freed itself both ecclesiastically from Riga and politically from the Teutonic knights, and placed itself directly under the Pope. The others were less fortunate, and the Order successfully resisted the joint efforts of the bishops and the Pope to place them in a similar position. [Sidenote: Missions in Asia.] The spread of Christianity among the tribes upon the Baltic coast, imperfect though it was, led to permanent results. In the second great field of missionary activity during this period the work of the Roman Church was more interesting than effective. It is difficult now to realise that in the fourteenth century emissaries from Rome had nominally organised large districts of Asia as part of the Christian Church. Nor was theirs the first announcement of the Gospel in those regions. Christians of the Nestorian or Chaldean faith could claim adherents from Persia across the Continent to the heart of China, and had even converted several Turkish tribes. [Sidenote: Prester John.]