In 1241 the first Mongol invasion of Poland occurred. In January the Mongols took Lublin and Zawichost. Bolesław, with his mother and wife, fled to Hungary at the side of his older sister Salomea, wife of the Hungarian prince Coloman, leaving his lands without his leadership. On 13 February the Mongols conquered and burned Sandomierz, and on 11 March he refused to participate in the Battle of Chmielnik. One month later, on 9 April, the Battle of Legnica took place, in which the army commanded by High Duke Henry II the Pious was defeated, and the duke himself was killed. After the defeat of the Hungarian army at the Battle of the Sajó River two days later (11 April) - where Prince Coloman was seriously injured and died shortly after - Bolesław V and his family (including Salomea, now a widow) fled to Moravia, and then eventually returned to Poland.