Latin: Ex qua die arcano is the incipit of the 4 March 1853 apostolic letter by which Pope Pius IX decreed the reestablishment of the episcopal hierarchy in the Netherlands.[1] Through it, the administrative area formerly known as the Dutch Mission was divided into dioceses. Utrecht was raised, once more, to a Roman Catholic archdiocese, and received the four suffragan dioceses of Haarlem, 's-Hertogenbosch, Breda, and Roermond.