All details of the crusade are from "Eric's Chronicle", which is largely propagandist in nature, written a century after the events, amidst internal unrest and a war against Novgorod. The chronicle says that the crusade took place between the Battle of Sparrsätra in 1247 and the death of King Eric (XI) in 1250, and presents the Tavastians ("taffwesta") as the Swedish opponents. According to the chronicle, the expedition was prepared in Sweden and then conducted over sea to a land on the coast, where the enemy was waiting.