Domagoj, Duke of Croatia

He took a more active role in the Adriatic Sea than his predecessors, encouraged the use of force and waged many wars, specifically with the Arabs, Venice and the East Francia.

Following the death of Duke Trpimir I in around 864, he was succeeded either by his son Zdeslav, who was shortly after deposed by Domagoj in a civil war,[1] practice, and Venetian ships were often attacked in the eastern Adriatic, which caused bad relations with Venice.

At the time of Domagoj's succession, Venice, under Doge Pietro Tradonico, began taking a more active role in the Adriatic Sea, and gained more independence from the Byzantine Empire.

[2] As soon as he came to power, the new Doge of Venice broke the long lasting peace treaty signed with Duke Mislav and attacked Croatia, which was still occupied with fighting over Trpimir's inheritance.

[3] In 865, Domagoj was forced to make an unfavourable peace with Venice, giving hostages as a guarantee for safe passage of Venetian ships in the Adriatic.

After ravaging Kotor, Kišan, and Budva, the Arabs started besieging Dubrovnik, which resisted the attacks for 15 months and was finally defended by the help of Byzantium.

[10] The reason for the Pope's sharing such concerns with Domagoj is that Bulgaria apparently bordered Croatia in some part of present-day Bosnia.

The papal project could have been to incorporate Croatian Christianity into the Bulgarian Church under the jurisdiction of Rome, thus encouraging the pro-Roman politics of Boris I of Bulgaria who then ruled much of the Balkans.

Domagoj was accused of attacking a ship which was bringing home the papal legates who had participated in the Eighth Catholic Ecumenical Council.

After the death of Louis the German, Carloman of Bavaria succeeded to the throne and Duke Domagoj decided to raise a rebellion and free Croatia from Frankish rule.