Dragutin's sister-in-law, Mary, had laid claim to Hungary after the death of her brother, Ladislaus IV. Dragutin was allegedly willing to support her and her son, Charles Martel of Anjou. Charles Martel, who regarded himself the lawful king of Hungary, granted Slavonia to Dragutin's son, Vladislav, in 1292, but most Hungarian noblemen and prelates remained loyal to Andrew III. Dragutin also sought a reconciliation with Andrew, and Vladislav married Constance, the granddaughter of Andrew's uncle, Albertino Morosini in 1293. Dragutin took advantage of the disintegration of Hungary during the last decade of the 13th century and became one of the dozen "oligarchs" (or powerful lords) who ruled vast territories independently of the monarch.