Complex sentence: Because of this, Vladislav began threatening Ragusa, which then had to turn to Ban Matej Ninoslav of Bosnia for help, and as the action against Vladislav was unsuccessful, Radoslav joined the court of the Epirote ruler Manuel in Dyrrhachium.
Split into simpler sentences: Because of this, Vladislav began threatening Ragusa, who then turned to Ban Matej Ninoslav of Bosnia for help. The revolt against Vladislav was unsuccessful, and Radoslav joined the court of Epirote ruler Manuel in Dyrrhachium.