Croatian–Bulgarian battle of 926

In 926 a battle was fought in the Bosnian highlands between the armies of the two Balkan rulers of the time: Bulgarian Tsar Simeon I, the great victor of the Battle of Anchialus over the Byzantine Empire ten years earlier, and King Tomislav of Croatia, the first king of the Croatian state.

It was fought in the area of the highlands of Eastern Bosnia near the Drina River, the border area between the Kingdom of Croatia and the Bulgarian Empire.

The Bulgarian ruler, Simeon, was a wise and able man with a restless and insatiable spirit. He spent his entire life fighting battles with neighboring countries. His basic aim was to defeat the Byzantine Empire and conquer Byzantium. To achieve his aim, Simeon overran the eastern and central Balkans several times, occupied Serbia and finally attacked Croatia.

Events preceding the war
After long wars and great success, capturing a larger part of the Byzantine territory in Europe, Simeon the Great was crowned at the church of Ohrid as "Tsar of all Bulgarians and Greeks" by the newly appointed Bulgarian patriarch 925. According to the juridical reasoning of the time, only the Pope and the Byzantine Emperor could bestow royal or imperial titles, and an emperor might be crowned only by a patriarch. Byzantine Emperor Romanus Lecapenus protested bitterly against Simeon's usurpation of the imperial title. The Patriarch of Constantinople, Nicholas Mysticus, did the same. In such a predicament, Simeon demanded Pope John X (914-928) send him an imperial crown and to recognize the head of the Bulgarian church as Patriarch. Naturally, Simeon had to promise to recognize the papal primacy in the Church. John X accepted Simeon's request and sent a solemn mission to Bulgaria, headed by Cardinal Madalbertus and John, illustrious Duke of Cumae. The papal mission reached Bulgaria at the end of summer or during the fall of 926, carrying a crown and scepter with which they would crown Simeon as Bulgarian Emperor.

When the papal mission arrived in Preslav, Madalbertus started long negotiations with Simeon and the representatives of the Bulgarian church. Probably, Madalbertus convoked a church synod in Bulgaria as he later did in Split, in Croatia, on his way back to Rome in 928. The negotiations regarding ecclesiastical matters were successful, and Archbishop Leontius was created Patriarch in Preslav, still during Simeon's reign.

Reasons for the war
Meanwhile, Simeon undertook imposing preparations for his crowning during the summer of 927. All of a sudden, he decided to wage a war against the Kingdom of Croatia.

The reason might have been that Tomislav received and protected the Serbs who were expelled by Simeon from Rascia. In all probability, however, the main reason was that Simeon, if crowned by the Papal Legate, feared an attack from the Byzantine Emperor supported by Tomislav. Emperor Romanus Lecapenus won the friendship of Tomislav some years previously, handing over the Byzantine Dalmatia to Tomislav and recognizing him as King of Croatia (Pope John X recognized Tomislav as King of Croatia in 925). During the summer of 926, Tomislav sent his troops to Italy to expel Saracens from the city of Sipontus, which belonged to the Byzantine province of Langobardia. This event could have been a sufficient proof to Simeon that the Croats took the side of the Byzantine Emperor and that they would support him actively in the future. Therefore, when Simeon sent a great army against the Croats, the Bulgarians were met by Tomislav's army in the mountainous region of Eastern Bosnia.

Battle
According to Byzantine historian Constantine Porphyrogenitus, King Tomislav was able to field an army of 100,000 foot soldiers, 60, 000 horse soldiers and 80 battleships (disputed). The strength of Simeon's army is unknown but was probably 30,000-70,000. The commander of the Bulgarian forces in this battle was Duke (Dux) Alogobotur.

The Croatian forces under the leadership of their king completely devastated the Bulgarian army. Key to Tomislav's triumph was likely the choice of terrain on which the battle took place: Croatian soldiers were probably more skilled in fighting in the mountainous terrain of the Bosnian highlands. The great military skill of the Croatian king and his cavalry was probably also a decisive factor against the Bulgarians.

Aftermath
Fearing a Bulgarian retribution, Tomislav accepted to abandon his union with Byzantium and make peace on the basis of the status quo, negotiated by the papal legate Madalbert.

Another consequence was, that a large part of Macedonia (theme) came again under Byzantine rule by a Peace agreement between the Bulgarians and the Byzantines in 927, because between these two events was a causal context.