Thomas is speculated to have been one of the driving forces behind the Battle of the Neva, a disputed Swedish-Novgorodian conflict that took place in 1240. The speculation is based on the 14th-century Russian Primary Chronicle mention of Finns and Tavastians fighting on the Swedish side, which according to some historians would have been organized by the bishop. However, as the Chronicle also lists the very unlikely Norwegians as allies, the information is regarded as mid-14th century propaganda, depicting Sweden as being in control of Norway, Finland and Tavastia.