At the same time, Naresuan was officially designated uparat, heir-presumptive to the throne of Ayothaya. Over the next decade, he matured to power and demonstrated his great military capabilities in several actions against Cambodia. In the midst of Ayothaya's difficulties in 1581-82, the young prince was sent to Pegu to represent his father in paying homage to King Nanda Bayin, who had succeeded Bayinnaung at the end of 1581. There he must have seen at first hand the factionalism and jockeying for power that soon threatened to shake the powerful Burmese Empire apart.