 In 1816 he was nominated Bishop of Philadelphia, but at his request the nomination was withdrawn and, on July 24, 1817, he was appointed Coadjutor bishop to Archbishop Francis Neale of Baltimore, and Titular of Stauropolis.The brief of the appointment had not reached Baltimore when Archbishop Neale died, and Maréchal was not consecrated Archbishop of Baltimore by Bishop Cheverus of Boston until December 14, 1817.Maréchal indicated that the most pressing problems facing the Archdiocese were the shortage of priests and rebellious trustees who wished to determine where those few be assigned.