By the early ninth century Croats had organised themselves sufficently to be recognised as a separate nation under the rule of their own dukes.
These dukes did however recognise the suzerainty, at least at first, of Charlemagne and his successors; but as Frankish power declined successive dukes such as Borna and Vladislav were able to gradually to assert their independence and by reign of Mislav in the 830s Croatia was effectively an autonomous state; the first permanent Slavic state in central Europe.
The first king Tomislav
In the year 910 Tomislav I became duke of Croatia and faced a number of challenges, first of all he had to defend Croatia from the threat of the Magyars and secondly he had to deal with Bulgaria, whose ruler Simeon the Great was attempting to expand his empire at the expense of that of Byzantium as well as threatening to conquer Serbia as well and dominate the Balkans. Tomislav was successfuly able to resist Magyar incursions and was therefore able to offer his services to the Byzantine emperor, who duly offered Tomislav the dignity of a royal title in return for his assistance. Tomislav was consequently crowned as the first king of Croatia in 923 with a crown sent from Byzantium. (Other sources say that Tomislav accepted a crown from the Pope in 924, both accounts may well be correct.)
Three years later when the Bulgarian Tsar Simeon the Great sent an army against Croatia it was entirely wiped out by Tomislav, thereby declaring his status as one of the powerful rulers of the region.
From Tomislav to Krešimir IV
Tomislav was succeeded by his younger brother Trpimir who was in turn followed by his son Krešimir. Now Kresimir was succeeded by his son Miroslav, but Miroslav’s younger brother Kresmir II fermented a rebellion and after a civil war took the throne after Miroslav was killed.
From Krešimir II the crown passed to his son Držislav and it was during his reign that the Byzantine Empire ceded control of Dalmatia to the Croatian kings in return for their support against the Bulgarians after which point the Croatian rulers styled themselves as ‘king of Croatia and Dalmatia’ (irrespective of whether or not they actually held all of Dalmatia at the time.)
After his death in 997 Držislav was succeeded by his son Svetislav, who was challenged by his two younger brothers Kresimir and Gojislav, who joined forces and after a civil war drove out Svetoslav. The two brothers ruled together until the death of Gojislav in 997, after which Krešimir III continued as sole ruler and was succeeded by his son Stjepan I.
Stjepan I was succesful in regaining control of Byzantine Dalmatia (lost during the civil war) and his son Krešimir IV was a notably energetic ruler who re-established the boundaries of Croatia to the same extent as they had been during the reign of Tomislav I.
From Krešimir IV to Hungary
Krešimir may well be recognised as the greatest Croatian king next to Tomislav, but when he died at the beginning of the year 1074, his lack of no sons had led him to designate his cousin Zvonimir as his heir and successor. Zvonimir’s claims were however ignored by the Croatian diet who selected one Slavac, the duke of Neretva, instead.
So Zvonimir’s supporters hired some Norman mercenaries from southern Italy who soon captured Slavac and took him out of the picture. The Venetians sought to take advantage and impose themselves on Croatia but the Pope intervented on Zvonimir’s behalf.
Zvonimir is remembered for the fact he aligned the kingdom with the Papal state, and whilst he wasn’t the first Croat ruler to cooperate with the Pope, the association between the church and the monarchy in the national memory dates from this time. Due to the influence of the Pope and Zvonimir’s rule there were no wars, the economy prospered and culture blossomed. (The famous Baska Tablet dates from this time.)
Zvonimir’s reign is therefore notable because it demonstrates the legacy of these Croatian kings, that is the strong connection between Croatia and the Catholic Church.
Zvonimir repeated the mistake of his cousin and died without male issue, leaving the succession a matter of dispute. One party supported a cousin by the name of Stjepan, whilst Zvonimir’s widow promoted her own claims and those of her brother ‘Ladislaus’ who just happened to be Ladislas king of Hungary.
Although Ladislaus was unable to get papal approval for his own claim to the crown of Croatia he managed to place his nephew Almoš on the throne instead. This was not to the liking of some elements in the Croatian nobility and when Almoš died they elected as king a certain Petar in 1093. But in the year 1097 Koloman (who had succeeded Ladislas as king of Hungary) invaded Croatia and defeated and killed Petar. (Who is considered in many ways as the last “real” Croat king.)
Croatia under foreign kings
Koloman therefore became king of both Hungary and Croatia but the result of Koloman’s conquest was not to unite the two kingdoms. Faced with problems elsewhere in his domains Koloman preferred to negotitate a settlement with the Croatians rather than engage in a protracted conflict.
Hence both Croatia and Hungary continued as separate and independent kingdoms, it was simply that the Croatians now accepted that their monarch would always be the king of Hungary. Therefore the kings of Hungary continued to be separately crowned as kings of Croatia, and Croatia continued to have its own diet and administrative pecularities. As far the Croatians were concerned they were simply sharing a king and got quite upset if anyone suggested otherwise. For example the Croatian diet refused to recognize Vladislav II as king of Croatia, because of a reference in his coronation charter to Croatia as a ‘subject kingdom’, until the Hungarians relented and agreed to form of words that took account of Croatian sensibilities.
This situation persisted until after the battle of Mohacs in 1526 when the succession in Hungary was disputed between Ferdinand of Austria and John Zapolya of Transylvania. The civil war between the two lasted until 1538 when they agreed the secret peace of Nagyvarad; Ferdinand withdrew his claim to Hungary in return for Croatia and Slavonia.
Croatia therefore passed into the hands of the Habsburg dynasty and the title king of ‘Croatia and Dalmatia’ became one of the many titles claimed by the archdukes and later emperors of Habsburg Austria. Accordingly the last crowned king of Croatia would have been the emperor Karl I of Austria.
The very last king of Croatia?
During World War II the Axis sponsored Independent State of Croatia came into being, sometimes known as the ‘kingdom of Croatia’ as an Italian prince by the name of Aimone Roberto Margherita Maria Giuseppe Torino, the 4th Duke of Aosta and Duke of Spoleto was proclaimed as Tomislav II, King of Croatia, Prince of Bosnia and Herzegovina, Voivode of Dalmatia, Tuzla and Temun on the 18th May 1941.
It seems as if this Tomislav II was nothing more than a figurehead if that, Croatia was run by one Ante Pavelic as poglavnik and he was in turn was a complete vassal of Italy and Germany. Accordingly no one has ever treated the claims of Tomislav II as anythig more than a joke and in any event he abandoned all claims to the throne on the 12th October 1943 following the Italian surrender.