Vukan broke into the Byzantine-held Kosovo Field in 1093, conquering and burning the town of Lipljan. Emperor Alexios I Komnenos personally headed the army to engage Vukan. However, Vukan withdrew to the fortified town of Zvečan and offered a negotiation. The emperor's acceptance points to the importance Vukan apparently had. Vukan seems to be aware of the power he had as he soon broke the truce again, attacking Kosovo again in 1093–1094. He defeated a Byzantine army led by the emperor's nephew John Komnenos and continued his advance, conquering initially the Kosovo Field area between Zvečan and Lipljan, but also advancing deeper into the Byzantine territory, plundering the surroundings of Skopje and acquiring Vranje and Polog Valley. Emperor Alexios I Komnenos again came to Lipljan in the summer of 1094, and Vukan again negotiated. He accepted not to attack Byzantine lands in the future, sending to the Byzantine Empire his fraternal nephews Uroš and Stefan Vukan and some 20 other cousins and "župans", as collateral. Before his death in c. 1112–1115, Vukan attacked the Byzantines once again in the spring of 1106. Before the fighting ended in November of the same year, Vukan once again defeated John Komnenos. Vukan also intervened in the neighboring Duklja. After the death of King Bodin, Vukan participated in the succession wars. He supported Kočapar in his opposition to Dobroslav II. In the Battle at Morača, Dobroslav II was defeated, captured and sent to Raška in chains. Kočapar and Vukan then took over Duklja, plundering a "very big part of Dalmatia". Vukan later married his historically-unnamed daughter to Vladimir, Kočapar's successor to the throne of Duklja. He then liberated Dobroslav, as he was a paternal uncle of king Vladimir.