Plessis was consecrated bishop in the Cathedral of Quebec on 21 January 1801, in the presence of the governor and officials of the province. The death of Bishop Denaut raised him to the episcopal sea of Quebec in 1806. He began his administration under difficult circumstances. Efforts were made to appropriate the property of the Jesuits and of the Seminary of Montreal to the uses of the state, to organize an exclusively Protestant system of public instruction, and to give a power of veto on the nomination of priests and the erection of parishes to the English crown.