Dušan may have also launched the campaign to aid his sister, Jelena, who married Mladen III Subic of Omis, Klis and Skradin, in 1347. Mladen died from Black Death (bubonic plague) in 1348, and Jelena sought to maintain the rule of the cities for herself and her son. She was challenged by Hungary and Venice, so the dispatch of Serbian troops to western Hum and Croatia may have been for her aid, as operations in this region were unlikely to help Dušan conquer Hum. If Dušan had intended to aid Jelena, rising trouble in the East precluded this.Pope Clement VI in 1335 addresses to King Stefan Dušan and request him to stop the persecution and that to the bishop of Kotor which is responsible for Roman Catholic Diocese of Trebinje return monasteries, churches, islands and villages, which some kings of Raška before him overtook.