Casimir III's first wife, Aldona of Lithuania, died on 26 May 1339. Two leading Polish noblemenZbigniew, chancellor of Cracow, and Spycimir Leliwitapersuaded Casimir, who had not fathered a son, to make his sister, Elizabeth, and her offspring his heirs. According to the 15th-century Jan Długosz, Casimir held a general sejm in Cracow where "the assembled prelates and nobles" proclaimed Louis as Casimir's heir, but the reference to the sejm is anachronistic. Historian Paul W. Knoll writes that Casimir preferred his sister's family to his own daughters or a member of a cadet branch of the Piast dynasty, because he wanted to ensure the king of Hungary's support against the Teutonic Knights. Louis's father and uncle signed a treaty in Visegrád in July whereby Casimir III made Louis his heir if he died without a son. In exchange, Charles I pledged that Louis would reoccupy Pomerania and other Polish lands lost to the Teutonic Order without Polish funds and would only employ Poles in the royal administration in Poland.