Tomislav: Unifying Croatia as its First King

Croatian Migrations: From Southern Poland to Dalmatia

Tomislav made history in 925 by defeating the advancing Hungarians and unifying Dalmatian and Pannonian Croatia to become the first-ever king of Croatia.

Although often perceived as a ‘young nation’, Croatia has a long history with its kings and national heroes. Arriving in their present homeland in the 7th century from their previous home in southern Poland, the Croats established a chain of their ‘barbaric’ princedoms in the former Roman province of Dalmatia. Most scholars see the movement of the Croats as a part of Slavic migration toward the South.

The Origin of the Croats: Controversies and Theories

The Croatian language is one of the Slavic languages, although the scientists cannot agree on the origin of the word ‘Croats’ (Hrvati), which does not have any Slavic root. From these doubts sprung various theories about Croats as a warrior elite establishing their dominance over the Slavic population, which had arrived in Dalmatia before them. Those Slavs lived there as the subjects of Avars, who started their advance South from the Pannonian valley against Byzantium at the beginning of the 7th century.

Even among those who subscribe to the notion that Croats were merely a warrior elite who imposed their rule over Slavic people, there remains disagreement over their Iranian or Gothic ancestry. Based on Bulgarian history, where an Asiatic warrior elite conquered Slavic territory in the southern Balkans, eventually adopting Slavic language and culture, this theory should not be considered implausible. However, it still lacks solid scientific evidence. Regardless of the possible origins, there is no doubt that the Croats and Croatian languages today belong to the Slavic group of peoples and languages.

Constantine VII Porphyrogenitus and the Croats

Constantine VII Porphyrogenitus, the Byzantine emperor from 912 to 959, wrote in his work ‘De administrando imperio’ that the Croats arrived in Dalmatia as allies of Emperor Heraclius to strike the Avars from the back as they threatened Constantinople. Constantine believed that the Croats managed to defeat the Avars and occupy Dalmatia, but there is no proof to support this claim.

The Avar-Slav Attack on Constantinople

After the unsuccessful Avar-Slav attack on Constantinople in 626, the Avars’ power weakened on the Balkan peninsula south of the Drava and Danube rivers. This area became filled with many Slavic princedoms, including Dalmatian and Pannonian Croatia. The border between these two princedoms was the same as the border between the Roman provinces of Dalmatia and Panonia. However, Pannonian Croatia did not extend north up to the Danube River, only to the banks of the Drava. The coastal urban areas and islands remained out of Croatian reach and were still a part of the Byzantine Empire, ruled from Constantinople.

A History of the Early Croats by Ante Mrkonjic
A History of the Early Croats by Ante Mrkonjic

The Political Map of the Western Balkans and the War between Franks and Byzantium

The western Balkans were politically divided when the war between the Franks and Byzantium began. The Croats, being the first Slavic nation to be Christianized from the western Church centres in Aquilea, took the Franks’ side in the war.

Frankish Overlordship

After the peace treaty between the Franks and Byzantium (813), both Croatian states remained in the Frankish sphere, while the Dalmatian coastal cities and islands remained under Byzantine control. During the Frankish rule, Dalmatian Croatia remained a staunch ally of the Franks, while Pannonian Croatia attempted to break free from the cruel rule of the Franks.

Knez Borna’s Dominance

Knez Borna of Dalmatian Croatia took an active part in suppressing the Knez Ljudevit rebellion in Pannonian Croatia. Although Borna’s raids in Pannonia were beaten back, his alliance with the Franks and the subsequent defeat and death of Ljudevit helped him establish his dominant political power in the western Balkans.

The Powerbase of the Future Croatian Kingdom

The area on the Adriatic coast, between the rivers Zrmanja and Cetina, excluding the Byzantine cities on the coast, became the power base of the future Croatian kingdom. This was the area where Knez Trpimir (c. 845–64) established his stronghold and the strong house of Trpimirović started its rise towards the throne of a united Croatia.

Tomislav was the direct heir to Knez Trpimir and inherited the throne of Dalmatian Croatia after the death of his father, Knez Muncimir (Mutimir), in 910. Despite challenges to their power on the throne of Dalmatian Croatia, the Trpimirović family continued to hold power.

Legacy of King Tomislav: Protecting the Croats and their Dominions

Western Balkans 925AD

Western Balkans, 925 AD

Inheritance of Dominions

Tomislav inherited his dominions in a very good state. He ruled over Dalmatian Croatia and united Pannonian Croatia with his territories, becoming the first king of Croatia. Despite being perceived as a young nation, Croatia has a long history with its kings and national heroes.

Encounter with the Hungarians

At the end of the 9th century, the Hungarians, pushed by the Pechenegs in the east, penetrated the Pannonian valley. They broke the territorial continuity of the Slavic areas between the Baltic and Adriatic Sea and destroyed the Moravian state in 892. The Hungarians started attacking the Bulgarian state, but the Bulgars repulsed them and engaged the Pechenegs to attack the Hungarians from the back. The Hungarians then concentrated in Pannonia, around the rivers Danube and Tisza, and started attacking Italy and Germany. They also took control over Pannonian Croatia, putting them in direct contact with Tomislav’s state.

Relations with Byzantine Cities

Tomislav’s relations with the Byzantine cities on the Adriatic coast were less troublesome. The Byzantine cities could not present any military threat to Tomislav, but he wanted to gain control over these maritime and merchant centres. The relationship between the Romans and the newcomers was never friendly, but the rulers of Dalmatian Croatia were never strong enough to enter into open conflict with Byzantium over these cities. Instead, they tried to build a relationship with the emperors in Constantinople to be recognized as protectors of the Dalmatian cities. The emperors were not against such arrangements, as evidenced by their willingness to grant protection over the Dalmatian cities to the Venetian doges. Tomislav was interested in imposing his protection over these rich cities in the form of a Byzantine official title.

Encounter with the Venetians

Earlier encounters in the 9th century showed that the Croats and the Neretljani could easily suppress the Venetians from the East coast of the Adriatic. One of the Croatian princes, knez Domagoj, was called “pessimus dux Sclavorum” by the Venetians because of his fierce attacks on their ships and territories. However, all plans of gaining control over the Dalmatian coast were impossible to fulfil while the Hungarians were threatening the northern borders.

Tomislav defeats Hungarians and Bulgars and unite Croatia

Tomislav’s Battles with the Hungarians

German and Venetian sources from the time period mention the fierce Hungarian attacks on their territories. Venetian sources often mention Hungarian raids down to the sea, indicating that Tomislav’s lands were also targeted.

The Annals of Dioklean Monk

The Annals of Dioklean Monk, a source from the 12th century Dioklea (now Montenegro), mentions many of Tomislav’s battles with the Hungarians in which he emerged victorious. Although the exact events are not known, we do know that Pope Leo X’s letter to Tomislav in 925 referred to him as “Tamisclao, regi Crouatorum…” marking the first time that a Croatian ruler was referred to as a king (rex).

Pope Leo X’s Letter

Pope Leo X’s letter to Tomislav in 925 referred to him as “Tamisclao, regi Crouatorum…” This was the first time that a Croatian ruler was referred to as a king (rex), indicating that Tomislav had defeated the Hungarians and established his border with Hungary on the river Drava. This unification of Pannonian and Dalmatian Croatia still holds today, with the river Drava being the border between Croatia and Hungary.

Thomas the Archdeacon

In his book Historia Salonitana, Roman Catholic cleric, historian, and chronicler Thomas the Archdeacon from Split described events from 914 and referred to Tomislav as dux, not rex. This indicates that the change from dux to rex must have happened sometime between 914 and 924.

The Crowning of Tomislav

The legend states that Tomislav was crowned on Duvno field, a location near the town of Tomislavgrad in southwestern Bosnia. This location was once the stronghold of the Illyrian tribe Delmati, who gave the Romans the name for the whole province on the eastern coast of the Adriatic.

The Battle Against the Bulgars

Just one year before Tomislav’s victory over the Hungarians, the Bulgars defeated Serbian prince Zacharius, who fled to Croatia. The Bulgars then attacked Croatia but were severely defeated by the Croats in 926 or 927 somewhere on the territory of modern-day Bosnia. Although Constantine VII Porphyrogenitus mentioned the battle where “Bulgars were all killed by the Croats,” he did not name King Tomislav.

Accepting the Split Synod

To gain control over the Dalmatian cities, Tomislav was willing to abandon the established church organization with Croatian liturgy. At the Split synod in 925, Tomislav accepted the dethronement of bishop Gregorius of Nin as the clerical primate in his kingdom and accepted the spiritual leadership of bishop John of Split, who was supported by Rome. The pope even sent a letter to Tomislav, calling him “the king of Croats.” The conclusions of the Synod of Split refer to Tomislav as “the king of Croatia and within the borders of Dalmatia.”

Evidence of Tomislav’s Rule over Pannonian Croatia and His Possible Death

It can be deduced that Pannonian Croatia was under the rule of Tomislav, as evidenced by the appointment of Bishop Gregorius to the town of Sisak. This was further confirmed at the second Synod in Split in 928, where both King Tomislav and the conclusions of the synod were present. After this event, there are only references to Trpimir II, who was either Tomislav’s younger brother or son. This leads to the conclusion that Tomislav likely passed away soon after the second Synod of Split in 928.

King Tomislav at throne in croatian ornament
King Tomislav at throne in croatian ornament
Council of Split 925 AD
Council of Split 925 AD



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