In the late 15th century, historian Ericus Olai claimed that Bishop Kol of Linköping (died c. 1196) had been the "Jarl of Finland" ("Dux Finlandiae"), possibly leading Swedish troops temporarily situated in Finland. He may have been in a military role similar to that of Jon Jarl, who allegedly spent nine years overseas fighting against Novgorodians and Ingrians at the end of the 12th century. Also noteworthy is the so-called First Swedish Crusade, which, according to several 15th-century sources, took place in 1150. The crusade is only known from later legends that presented the expedition (if it ever took place) as a Christian mission, headed by a saint king to baptize heathens. However, it seems to have followed the exceptionally edgy 1140s with both the Yem and Swedes fighting against Novgorod. Some historians have seen it as a direct reaction to the failed Yem expedition in 1149, associating it with the co-operation mentioned by the Pope 20 years later. In 1221, Pope Honorius III was again worried about the situation after receiving alarming information from the Archbishop of Uppsala. He authorized the unnamed Bishop of Finland to establish a trade embargo against the "barbarians" that threatened the Christianity in Finland. The nationality of the "barbarians", presumably a citation from Archbishop's earlier letter, remains unknown, and was not necessarily known even by the Pope. However, as the trade embargo was widened eight years later, it was specifically said to be against the Russians. Russian sources mention Swedish-Yem co-operation in 1240 at the earliest; it was then that  were mentioned as one of the Swedes' allies in the little-documented Battle of the Neva. The first reliable mention of Yem being a part of Swedish forces is from 1256, seven years after the conventional dating of the so-called Second Swedish Crusade. The final known conflict between Yem and Novgorod took place in the 1220s, following decades of peace, at least in the chronicles. After having secured his power in Novgorod by 1222, Grand Prince Yaroslav II of Vladimir organized a series of attacks against Estonia, Yem and Karelia. The offensive against Yem took place in winter 1226–27. The same winter Yaroslav, son of Vsevolod left Novgorod over the sea against Yem where no else Russian prince had been able to dwell; and he conquered the land and returned to Novgorod praising God with many prisoners.