The battle in the Bosnian Highlands took place at the beginning of May 927 between Croatian and Bulgarian forces.
The battle in the Bosnian Highlands took place at the beginning of May 927 between Croatian and Bulgarian forces. Emperor Simeon of Bulgaria captured much of Byzantine territory in Europe and crowned himself "Emperor of Bulgaria" in 913. In 924, Simeon sent a large army against Zaharia in the Principality of Serbia. The Bulgarian army ravaged Serbia and forced Zaharia to flee to Croatia, and Serbia was annexed to Bulgaria. In 924, Tomislav defeated the Hungarian duke Zsoltan in Lower Pannonia and annexed it to his state. After Emperor Romanus I Lekapenos granted him some form of control over the coastal cities of the Byzantine theme of Dalmatia and was rewarded with a portion of the tribute collected from the cities, Tomislav proclaimed himself king around 925. Tomislav received and protected the Serbs who were expelled by Simeon. For Simeon, these events were proof enough that the Croats had sided with the Byzantine emperor and that they would actively support him in the fut