Vseslav was the
grandson of
Yaroslav I, Grand Prince of Kievan
Russia. Starting in
1044, Vseslav, nicknamed something that translates to "the
Magician," ruled the
city of Polotsk, as his father had before him, but while his uncles and cousins were fighting over the successions to other cities in
1065, Vseslav took the opportunity to try and expand the territory of Polotsk at the expense of that of
Novgorod, a much more well-established and historic city.
His uncles, led by Grand Prince Izyaslav I, did not like this and sent armies against him. The battle was inconclusive, as the coalition did not manage to capture Vseslav or anything that would really keep him down. It was actually in supposed peace negotiations that the three brothers broke their pledge of safety and took Vseslav captive, putting him in prison in Izyaslav's city of Kiev in 1067.
Russia was attacked the next year by hostile Southern tribes the Polovtsi; Izyaslav and his brothers sent armies which were defeated by the intruders, so each fled to his home city. The people of Kiev wanted Izyaslav to lead a Kievan army against the invaders, but he refused. So, they revolted against Izyaslav (who fled to his wife's relatives in Poland), and released Vseslav from prison to make him Grand Prince. He didn't really have a chance to lead an army against the Polovtsi; his uncle (Izyaslav's brother, the later Sviatoslav II) managed to defeat them on his own. After seven or eight months, Izyaslav came back to Kiev with a Polish army and Vseslav fled back to Polotsk.
Shortly thereafter, Vseslav fled Polotsk because Izyaslav was sending his son there after him. For three years he collected armies and support, and then was able to take back the city, and continued to rule it for thirty-odd more years, though he stopped trying to expand his territory at the expense of other Russian cities. He died in 1101, one of the few to survive losing the Grand Prince's throne for long.