and were to remain under Croatia. Tsar Simeon sent Duke Alogobotur to drive the Serb refugees further into Croatia, causing outright war in ca. 926. The climax of the war was the Battle of the Bosnian Highlands that same year, when Croatian forces under the command of King Tomislav completely defeated the Bulgarian forces under the command of Alogobotur, killing most of the Bulgarians in the battle. The Croatian victory was so decisive and the battle so big that contemporary sources greatly overestimated Croatia's Army at 160,000 men, with a slightly bigger force on the Bulgarian side. This was the only battle Tsar Simeon ever lost. Since both rulers maintained good relations with Pope John X, the pope was able to negotiate an end to the war soon afterward without any further border changes. Although the eastern border was extended down to the river of Bosnia, the Croatian realm was greatly strengthened both militarily and in natural resources: it emerged from the war as one of the most modern realms of the period and was able to consolidate a moderately sized navy. On the same day as the battle Simeon died in Preslav and his successor Peter I faced internal difficulties and revolts by his brothers Michail and Ivan. The Serbs were able to take advantage of this situation and many of them returned by 931 to their homes in the renewed Serbian realm, thus terminating Croatia's short-lived Bulgarian neighbor at the east. Third war In the second half of the 10th century, the Croatian realm was ruled by Stjepan Držislav. Stjepan formed an alliance with the Byzantine Empire, which in turn recognized him as the King of his lands. After his death in 997, his son Svetoslav Suronja continued his pro-Byzantine policy. His brothers Krešimir III and Gojslav did not want Svetoslav as ruler and attempted a coup d'etat, asking the Bulgarian tsar Samuil for help. Answering their call, Samuil went on a rampage in 998 and razed the Dalmatian cities of Trogir and Split, but he was stopped at the siege of Zadar. The Bulgarian forces then returned home, using the Bosnian route. Territory taken by Samuil during the war was given to Krešimir III and Gojslav, who, with further Bulgarian support, won the Croatian civil war and took over the realm in the year 1000. Svetoslav Suronja, a Byzantine and Venetian ally, was sent to exile in