After the death of Dřislav, his eldest son Svetoslav Surya ascended to the throne, but his brothers Kresimir and Goislav revolted, provoking the largest civil war in the history of the Kingdom of Croatia. The brothers enlisted the support of the Tsar Samuil, who in 998 occupied and ravaged the whole of Southern Dalmatia right up to Zadar, including the major port cities of Trogir and Split, after which he returned through Bosnia. He handed over the entire conquered territory under the authority of the brothers Kresimir and Goislav. Svetoslav tried to enlist the support of the Republic of Venice, where in 1000, Doge Pietro II Orseolo led the Venetian fleet to the eastern Adriatic and began to seize the cities. Venetians took the islands in the Kvarner Bay, the capital of Croatia – Biograd na Moru, and then all the largest cities of Croatia – Trogir , Zadar , Split. Also, the Venetians conducted successful naval campaigns in Pagania, established control over Korcula and Lastovo and demanded that the doge be given the title of “Duke of Dalmatia”. However, after the death of Pietro Orseolo, Svetoslav Suronya was overthrown by his brothers and was forced to flee the country with his son.
Kresimir III, at the beginning, ruled in collaboration with his brother Gojslav (1000-1020). They attempted to reclaim the Dalmatian cities. Until 1018, they were successful, but soon were defeated by the Venetians, who came to the aid of the Lombards. In 1020, Kresimir, under unclear circumstances, killed his brother Gojslav, which caused discontent among the people and the Pope, who refused to recognize the fratricide as the legitimate king. The cause of the murder was unclear, there were suggestions that the brothers disagreed on the future political orientation of Croatia, Kresimir III fully supported the papal throne, Gojslav preferred patronage of Byzantium.
The papal legate Maynard was sent to Croatia to investigate the murder, in 1027 Kreshimir swore his innocence, but no one believed him. Stepan Svetoslavich, the son of Svetoslav, decided to take advantage of the situation in the country. Stepan did not ascend to the throne, but with the help of the Hungarian troops he established himself in Slavonia, which from now until 1074 will be called Croatian land only formally, ruled by the Svetoslavic dynasty. Anarchy in the country continued until the death of Crechemira III in 1030.
Stephen, who came to power after the death of his father in 1030 and ruled until 1058, was going to march on the Venetians and Pagania in order to return the lost lands. However, Croatia was again very weak and Stephen did not dare to fight the Venetians. The king made an alliance with Byzantium, recreated the fleet again, and gradually, by purely diplomatic means, he again achieved the actual transfer of the trade cities of Dalmatia to Croatian power. His reign was one of the few completely peaceful reigns. Stephen I took the title of King of Croatia, Bosnia and Dalmatia, he ruled the territory right up to the borders of the Dubrovnik Republic, which is confirmed by land donations, which he made to Ragusa (Dubrovnik) in 1050.
Revival of Croatia
The reign of King Petar Kresimir (1058-1074) is considered the time of Croatia’s ascent to the peak of power, when the Croats were successful in wars, domestic policy, and the acquisition of significant territories. Petar Kresimir forced the Byzantine emperor to recognize him as the ruler of all Dalmatia, including their cities. Also, Kresimir IV maintained a close alliance with the Roman church, which allowed him to interfere in the religious policy of Croatia, which contributed to the further strengthening of his power. However, the intervention of the Roman priests destroyed the verb and the old rites in parts of the land of Istria. After numerous conquests of Petar Kresimir, Croatia counted 12 districts, the number of which exceeded the number of Croatian lands under Tomislav I. Kreshimir finally subjugated Pagania to Croatia, and also spread its influence in Zahumlia, Travunia and Dukla. The new capital of Croatia after the loss of Biograd was the city of Sibenik.
As Petar did not try to maintain good relations with Byzantium, he nevertheless had to enter into conflict. In 1072 he supported the Bulgarian and Serbian uprisings against Byzantium. In response, Byzantium sent troops led by the Norman Count Amiq to besiege Rab Island. The Normans could not seize the island, but captured King Petar Kresimir. The people, who loved their ruler, were forced to make concessions: Split, Trogir, Biograd and Nin withdrew to the Normans. However, the Normans were soon evicted from Italy, and the Croatian cities passed to the hands of Venice. The death of Kresimir IV in 1074 thwarted the direct branch of the Trpimirovich dynasty.
Croatia under Demetrius Zvonimir
Petar Kresimir had no sons. The reason for which he did not appoint Stepan’s nephew heir is unclear; perhaps this was due to the poor health of Stephan, perhaps with the king’s desire to reintegrate Slavonia into Croatia, ruled by the younger branch of Trpimirovich. Ban Demetrius Zvonimir (1075-1089) was proclaimed heir to the throne in 1070. However, after the death of the king in 1073, the Dalmatian nobility, who did not want to see a native of Slavonia on the throne, refused to recognize Zvonimir as king and in 1074 elected the nobleman Slavac to be the new king.
These elections against the will of the pope and the wishes of the rich Dalmatian cities led to the fact that the Norman forces were called against Slavac. According to the message of the old Croatian chronicle, Slavac was defeated on Rab and thrown into prison. The period of the interregnum of 1074-1075 ended with the assertion on the throne of Demetrius Zvonimir with the support of Pope Gregory VII.
Zvonimir helped the Norman duke Robert Guiscard in the fight against Byzantium and Venice in 1081 and 1085. Zvonimir helped the Normans pass through the Strait of Otranto and occupy the city of Durres. His troops also helped the Normans during their campaign on the coast of Albania and Byzantium. Consequently, in 1085, Byzantium transferred all its rights to the Dalmatia of Venice.
The reign of Zvonimir is assessed as peaceful and successful. During the reign of Zvonimir, nobility titles used in Medieval Croatia began to be used in Europe and vice versa. Zhupaney and bans were called barons, and European nobility sometimes called themselves “vlastelin” (lord).