Pope John X
Since Croatia was harboring Bulgarian enemies and was allied to the Byzantine Empire, Simeon decided to attack Croatia and sent an army led by Duke Alogobotur, but Tomislav cut off his advance into Croatia and completely destroyed his army at the Croatian–Bulgarian battle of 926 which probably took place in the eastern part of Bosnia. After the death of Emperor Simeon in 927, Pope John X sent his legates with Bishop Madalbert to mediate between Croatia and Bulgaria, thus restoring peace.