The siege of Tartu took place in 1224 and resulted in the fall of the last major center of Estonian resistance in the mainland provinces to the Christian conquest of Estonia. Background In 1208, the Livonian Brothers of the Sword launched a crusade against the pagan Estonians, who had been raiding into the Latgalian and Livonian territories to the south which had recently been conquered by the Order. In 1219 Denmark joined the Crusade, and in 1220, Sweden. The Estonians were able to annihilate the Swedish presence, but by the winter of 1220 nearly all of continental Estonia had been conquered by the Germans and Danes, and the population declared Christian. The uprising of 1223 In 1223, there was a general anti-Christian uprising in the subjugated continental part of Estonia. All Germans and Danes who fell into the hands of the Estonians were put to the sword, and some of the priests ritually sacrificed to pagan gods. Estonians reoccupied all the fortresses after the German garrisons had been killed. In order to secure the initial military success, mercenary Russian troops were invited from Novgorod and Pskov and stationed in several key fortresses, such as Viljandi and Tartu. The identities of the Estonian leadership in Tartu is not known. The commander of the Russian mercenaries was Vyachko, who in 1208 had lost his dominion in Koknese to the combined forces of the Sword Brethren and Livonians. He was given two hundred men and money by the Novgorod Republic so that he could establish himself in Tarbatu (present-day Tartu), or any other place "that he could conquer for himself". First siege of Tartu In the winter of 1223/1224, the Germans gradually managed to reconquer most strongholds in mainland Estonia. Tartu remained the last center of resistance in South-Estonia. In addition to the local population from Ugandi, many diehard freedom fighters had gathered there from Sakala and other neighboring provinces (vicinas omnes provincias). The crusaders laid siege to Tartu after Easter in 1224, but were forced to leave after only five days of fighting. The bishops sent a delegation to Vyachko and asked him to give up the "heathen rebels" in the fortress and leave them, but he chose to stay because the "Novgorodians and Russian princes had promised him the fortress and the surrounding lands" if he could conquer them for himself. Second siege of Tartu On 15 August 1224 the crusader