Complex sentence: He was crowned king shortly after the death of his father in early June 1162, but his right to the crown was challanged by his two uncles, Ladislaus and Stephen, who had fled to the Byzantine Empire during his father's reign.
Split into simpler sentences: He was crowned king shortly after the death of his father in early June 1162. His right to the crown was challanged by his two uncles, Ladislaus and Stephen, who had fled to the Byzantine Empire during his father's reign.