The Church reform of Peter I introduced what some believe was a period of Caesaropapism in the history of the Russian Orthodox Church, when the church apparatus effectively became a department of state.
Previously, the Russian Tsars had exerted some influence on church operations; however, until Peter's reforms the church had been relatively free in its internal governance. Following the model of the Byzantine Empire, the Tsar was considered to be the "Defender of Orthodoxy". In this capacity he had the right of veto over the election of new bishops, and upon the consecration of new bishops he would often be the one to present the crozier to them. The Tsar would also be involved in major ecclesiastical decisions. In 1551, Tsar Ivan IV summoned the Synod of a Hundred Chapters (Стоглавый Собор), which confirmed the inviolability of church properties and the exclusive jurisdiction of ecclesiastical courts over clergy, and the norms of church life were regulated. The Great Synod of Moscow in 1666-1667 was also presided over by the Tsar.
Peter the Great ended up losing the support of the Russian clergy over his reforms. Local hierarchs became very suspicious of Peter's friendship with foreigners, the shaving of his beard, and his alleged Protestant propensities. The Tsar did not abandon Orthodoxy as the main ideological core of the state, but attempted to start a process of westernization of the clergy, relying on those with a Western theological education, although Peter at the same time remained faithful to the canons of the Eastern Orthodox Church. Peter unintentionally caused "Ukrainization" of the Russian Church, inviting Ukrainian and Belorussian clergy (mostly graduates of the Kiev-Mohyla Academy) from the buffer regions of the Empire into Russia. As a result of this, by the middle of the 18th century the majority of the Russian Orthodox Church was headed by people from Ukraine (Little Russia or Galicia). Between 1700 and 1762, out of the 127 hierarchs who headed cathedrals in Russia 70 were from Ukraine and only 47 from Russia (the rest originating from other regions).