and stop any aid to the Prussians. Prussians were compelled to sign the Treaty of Christburg on 7 February 1249. The treaty provided personal freedom and rights to newly converted Christians. It formally ended the uprising, but already in November 1249 the Natangians defeated the Knights at the Battle of Krücken. The skirmishes lasted until 1253 and some sources cite this year as the end of the uprising. At that point the treaty ceased its political power but remained an interesting historical document. The great Prussian uprising (1260–1274) Preparation and tactics The major revolt began on 20 September 1260. It was triggered by the Lithuanian and Samogitian military victory against the joint forces of the Livonian Order and Teutonic Knights in the Battle of Durbe. As the uprising was spreading through Prussian lands, each clan chose a leader: the Sambians were led by Glande, the Natangians by Herkus Monte, the Bartians by Diwanus, the Warmians by Glappe, the Pogesanians by Auktume. One clan that did not join the uprising was the Pomesanians. The uprising was also supported by Skomantas, leader of the Sudovians. However, there was no one leader to coordinate efforts of these different forces. Herkus Monte, who was educated in Germany, became the best known and most successful of the leaders, but he commanded only his Natangians. The Prussians besieged many castles that the Knights had built and could not send large armies to fight in the west. Prussians were not familiar with Western European siege tactics and machinery and relied on siege forts, built around the castle, to cut the supplies to the garrisons. The Teutonic Knights could not raise large armies to deliver supplies to the starving garrisons and smaller castles began to fall. Those castles were usually destroyed and the Prussians manned just a few castles, notably one in Heilsberg (Lidzbark Warmiński), because they lacked technology to defend the captured castles and organization to provide food and supplies to stationed garrisons. On 29 August 1261 Jacob of Liège, who negotiated the Treaty of Christburg after the first uprising, was elected as Pope Urban IV. He, having an inside scope on events in Prussia, was especially favourable to the Teutonic Knights and issued 22 papal bulls in three years of his papacy calling for reinforcements to the Knights. However, the reinforcements were slow to come as dukes of Poland and Germany were preoccupied with their own