 Arguably, these power struggles were instigated by the Russian tsar, in an effort to undermine the authority of the Cossacks.During his reign, Bohdan Khmelnytsky managed to wrestle Ukraine out of Polish domination, but was later forced to enter into a new and uneasy relation with Russia in 1654.His successor, general chancellor and close adviser Ivan Vyhovsky, was left to deal with Moscow's growing interference in Ukraine's internal affairs and even overt instigation of a civil war by way of supporting Cossack factions opposing Vyhovsky.