Tavastian uprising

The Tavastian uprising, also sometimes called the Häme uprising, was a uprising by Tavastians in Tavastia, Finland in the winter of 1236–1237. The rebellion was against the Kingdom of Sweden and against the Catholic Church. The Tavastian rebels received aid from the Novgorod Republic, which sought to diminish Swedish influence in Finland in order to bolster its own position.

Pope Gregory IX described the event in a papal letter dated 9 December 1237 and addressed to Jarler, who was the Archbishop of Uppsala. He describes how the Tavastians returned to their pagan beliefs from Christianity and destroyed a Catholic church in Häme. He goes into detail describing other atrocities committed by the Tavastians. This has been seen as papal propaganda. Finally, he issued a call for a crusade against the rebels. Ultimately, harsh measures were employed to quell the uprising.

Due to the Mongol Invasion of Russia in 1237, support from the Novgorod Republic for the Tavastian rebels wained. Following the uprising, the Swedes held the Second Swedish Crusade against the Tavastians and used the Pope's message as further justification for the crusades.