The Baltic crusades of the twelfth and thirteenth centuries were in principle aimed at converting infidels and establishing a new Christian plantation in the wilderness, but the contemporary narrative sources repeatedly tell of crusaders systematically chasing down pagans and annihilating them with the sword. Men, women, and children were killed without discrimination, and fertile and inhabited land laid waste. Field crops, houses and villages, wooden idols and their sacred buildings, and pagan prisoners of war were burned and cremated into ash and nothing.

Two apparently opposing understandings of warfare seem to have existed simultaneously among the religiously well-educated authors whose writings from the decades around 1200 open a fascinating – and often scary – window to the religious border societies in the north. On the one hand, it was argued theologically and legally that warfare should be regulated, limited, and aimed at creating peace. The infidels shared with Christians certain basic human rights which protected them against arbitrary violence, and it was repeatedly emphasized that belief could only be given willingly, and thus that conversion could never be forced. On the other hand, the same authors argued for compulsory conversion and indiscriminate killing, if crusaders were inflamed by the zeal of God, and in order to avert the wrath of God from befalling the Christians.

These apparently contradictory concepts of conversion could perhaps be explained as formulations from a period of transition, from a traditional peaceful mission of individuals to a more powerful and violent mission of organized armies. This has been argued for the Baltic area by a number of scholars who have traced this transformation to the last decade of the twelfth and the early thirteenth centuries. One of today's most widelyrespected scholars on mission and the spread of Christianity in northern Europe, Professor Christian Krötzl, wrote in his book from 2004 about ‘The return of the sword mission to the Baltic’ and the change in the ideology of mission in the twelfth century. One of the chapters in his book is programmatically entitled ‘Livonia: From Preaching to the Sword’. Christian Krötzl’s work has contributed to and refined a discussion that has been ongoing throughout the twentieth century and likely began among historians much earlier – the use of force in spreading the faith of Christianity.