The most prominent struggle for power was the conflict that erupted after the death of Yaroslav the Wise. The rival Principality of Polotsk was contesting the power of the Grand Prince by occupying Novgorod, while Rostislav Vladimirovich was fighting for the Black Sea port of Tmutarakan belonging to Chernihiv. Three of Yaroslav's sons that first allied together found themselves fighting each other especially after their defeat to the Cuman forces in 1068 at the Battle of the Alta River. At the same time, an uprising took place in Kiev, bringing to power Vseslav of Polotsk who supported the traditional Slavic paganism. The ruling Grand Prince Iziaslav fled to Poland asking for support and in couple of years returned to establish the order. The affairs became even more complicated by the end of the 11th century driving the state into chaos and constant warfare. On the initiative of Vladimir II Monomakh in 1097 the first federal council of Kievan Rus' took place near Chernihiv in the city of Liubech with the main intention to find an understanding among the fighting sides. However, even though that did not really stop the fighting, it certainly cooled things off.