Dragutin supported his brother's attacks against the Byzantine territories in Macedonia in the 1290s. After Milutin had made peace with the Byzantine Empire in 1299, dozens of Serbian noblemen, who had benefited from the war, moved to Dragutin's realm. Tensions between the two brothers grew rapidly, most probably because Milutin wanted to secure the succession in Serbia for his own sons. In 1301, open war broke out and Milutin occupied Rudnik after taking it from Dragutin. According to Ragusan reports, a peace treaty was made in late 1302, but Dragutin's troops or allies pillaged Milutin's silver mines at Brskovo in 1303. The armed conflict lasted for more than a decade, but its details are unknown. The parties allegedly avoided fighting pitched battles and Dragutin kept his realm almost intact, although income from the silver mines enabled Milutin to hire mercenaries.