 Upon the death of Sviatoslav Yaroslavich in 1077, his brothers Vsevolod Yaroslavich and Izyaslav Yaroslavich started a bitter rivalry over the Kievan throne.Vsevolod left Chernigov and headed towards Izyaslav, who had set out on a military campaign against Kiev.Boris took advantage of his uncle's absence and seized control of Chernigov.