When Pope Pius IX, with the apostolic letter "
Ex qua die", reorganized the
Catholic Church of the Netherlands,
Utrecht was raised once more to an archbishopric, and Zwijsen was named the first
archbishop; as administrator he also ruled the
diocese of
's-Hertogenbosch. His connection to the Dutch government, one he had obtained through his friendship with William II, was most probably a factor in this appointment. He took up with great energy and caution the organization of the restored
archdiocese, even though he had preferred it to be based in s-Hertogenbosch. By numerous excellent decrees he provided for the improvement of discipline, the encouragement of
orders and of church associations and for the establishment of
Catholic schools. In 1857 opened the diocesan seminary for the training of a competent clergy. In 1858 the cathedral chapters of the archdiocese were organized and in 1864 the first provincial
synod was held. ==Resignation and death==