 Yaroslav's eldest surviving brother, Sviatopolk I of Kiev, killed three of his other brothers and seized power in Kiev.Henry II's support of Yaroslav was in direct opposition to not only Sviatopolk but to Bolesław I as well.Years before, Bolesław I had married one of his daughters to Sviatopolk, making the new Kievan Grand Duke a son-in-law to the Polish Duke.