y the beginning of the XIII-th century the pagan past of Europe belonged already to legends. Everywhere Christianity had triumphed and become not only the prevailing religion, but also a mainstay of feudalism .  Everywhere, except along the eastern coast of the Baltic sea. There the Baltic peoples continued to adhere to the ancient way of life. Christian Europe had been busy with the Crusades to the Holly Land, but there the tide had turned.  The remnants of the crusading armies were besieged in a few coastal enclaves and it was evident that their time was running out.  Supply and reinforcement across a distant sea harassed by Muslim fleets had proven untenable.  By this time Christian Europe was hardened by religion driven wars which had lasted a century.  Society had changed in response to the demands of war, and the hierarchy of the Church had not escaped its corroding influence .  Thus now there were even monastic orders whose purpose of existence was not to pray or perform good deeds, but to wield the sword in the name of Christ.   No matter that the Prince of Peace  had said that those who - "Raise the sword shall perish by it!".  Mans capacity for self justification and sophistry is boundless.  The sword was unsheathed, justifications were added as an afterthought, and the newly  unemployed knights looked for other heathen lands to conquer.    It was then that the stubborn Baltic tribes were remembered and the Northern Crusades began.
 

The Northern Crusades carried on against the Baltic pagans lasted longer and terminated considerably later then the Crusades in the Holy Land. Like the Mediterranean Crusades they consisted of an entire series of campaigns. The first crusaders reach the Baltic lands by sea. They are spearheaded by the northern German states who seek to gain a foothold at the mouth of Dauguva, the principal river flowing through the lands of the Livs, the Selonians and Latgalians living in the territory roughly coinciding with present day Latvia. Calls for a crusade is obtained from Pope Innocentus II a crusading army is raised and after some battles a stronghold which was to grow into the city of Riga is established. The Danes and Swedes are not far behind, but they have a rocky start, because they quarrel among themselves who shall christen and subjugate the Estonians. After several decades of fighting the initial foothold in the north has been extended and a fierce crusader campaign is initiated against the Prussians, the southern flank of the Baltic peoples. Raids against the Prussians have been carried on for over a century, but they do not make headway until the Teutonic Order is invited by the polish principality of Mazovia to and lead a crusade sanctioned by the highest authorities of Christian Europe.

The Teutonic Order is wealthy and well connected, their head master von Salza is a confident of Emperor Friedrich the II-nd and has ready access to Pope Gregory IX. Consequently the attack against the Prussians is an international effort, with the support, including exhortations and promises of absolution of all sins granted by Popes. Almost on an annual basis crusading armies invade and ravage the Prussian lands, the inhabitants are subjugated or exterminated, castles are built and fortified towns, complete with imported settlers, are established. However, in spite of extensive international help progress is slow. It takes over 60 years to subjugate the Prussians in the south, more then that to subdue the Curonians and Ziemgalians in the north. The front lines stall completely once the Lithuanian and Samogitian lands are reached. Its almost as if trench war had arrived eight hundred years early, except that the stall mate lasts not month or years, but centuries.

 
Pagan beliefs were not something that one acquired systematically.  It was something that one was born to and which became and integral part of a persons life view during the years of growing to adulthood. As a result it is a system of beliefs that is very difficult for an outsider to understand, the difficulty is made more severe by the circumstance that understanding has to be attempted on scant, scattered and contradictory evidence. For pagan religions were very rarely (maybe even never) proselytizing. They were religious systems that had evolved in specific times and places, that were being transmitted as part of the cultural heritage. Such religious systems usually did not desire outsiders and consequently there was no need to explain it. Thus even when the pagans in question where literate, (the ancient Greeks and Romans are the most prominent examples), consistent explanations of the tenets of beliefs were not provided. There is no pagan equivalent of the Talmud, the Bible or the Koran.

But the beliefs were strongly held. Several centuries of war defending them eloquently attest to this.