Roman Catholic Diocese of Trebinje–Mrkan

The Roman Catholic Diocese of Trebinje–Mrkan is an ecclesiastical territory or diocese of the Catholic Church in Herzegovina. It is the oldest and smallest Catholic diocese of Bosnia and Herzegovina.

The diocese was formed sometime before the year 1022. An exact date is not known, but church officials decided to celebrate the diocese's millennium in 1984, estimating its foundation at 984. The diocese has its episcopal seat in the city of Trebinje. However, from 1361 to 1391 it was relocated to the island of Mrkan, thus taking on the present double name. Pope Clement VI in 1335 addresses to Stefan Uroš IV 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.

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