of his uncle. The situation worsened when, in October 1223, Odonic surprisingly attacked and managed to conquer the town of Ujście, and soon afterwards (in 1225) the adjacent district of Nakło. Spindleshanks' situation became more complicated after the loss of Lubusz in 1225, captured by Louis IV, Landgrave of Thuringia, who took advantage from the constants fights of the Greater Poland Duke with his nephew and could conquer this important territory. New phase in the War against Władysław Odonic. Defeat at Ujście The decisive battle between uncle and nephew took place in 1227. Spindleshanks sent an army under the command of the voivode Dobrogost besieged Ujście, but he couldn't take the strong local fortress, and on 15 July, Odonic surprisingly attacked the voivode, who was completely defeated and killed. Thanks to this victory, Władysław Odonic was able to take control over almost all Greater Poland; however, Odonic's ally Swantopolk II unexpectedly broke the existing treaty, took Nakło and proclaimed himself Duke, ended his homage to Leszek I the White. Congress of Gąsawa and murder of Leszek I the White The alliance of his nephew with the Pomeranian ruler put Spindleshanks' rule in jeopardy, and he feared that he could lose the remain of his lands; so, he decided to make a pacific solution to his disputes with Odonic. On St. Martin's day (11 November) 1227 a solemn congress of Piast rulers, bishops and nobles in the small Kuyavian district of Gąsawa was convened, where this and others delicate issue were discussed in order to take further steps. In addition to the instigator of the reunion, Leszek I the White, were also present his brother Konrad I of Masovia, Henry I the Bearded, Wladyslaw Odonic (whose assistance is disputed by historians), the entire episcopate and numerous representatives of Polish magnate families. For unknown reasons, Władysław Spindleshanks didn't appear in Gąsawa, although is believed that both Archbishop Wincenty of Gniezno and Bishop Paweł II of Poznań watched his interests. Nobody expected the tragedy, which occurred on the morning of 24 November: during a short break between the deliberations in the town of Marcinkowo Górne, a group of Pomeranians attacked both Leszek I the White and Henry I the Bearded; Leszek I was killed and Henry I severely wounded, but did survive. Contemporary sources and later historiography clearly recognize Swantopolk II as the crime's author. However, some historians believed that Władysław Odonic was