[citation needed] He was the oldest son of king Stephen Držislav, from whom he received the title of duke, and was designated as his successor.
After the death of their father, his brothers Krešimir III and Gojslav started organizing a rebellion against him since Svetoslav rejected sharing power over the kingdom.
[2] Taking the Croatian raids as a casus belli, the Venetian Doge Pietro II Orseolo launched a campaign in Dalmatia against Croatia in 1000.
In May, Croatia lost the islands Cres, Lošinj, Krk and Rab to the Doge, who was eventually received in Zadar and recognised as its master.
Svetoslav sent envoys to the city offering peace, but the Doge declined and decided to further his campaign.