[3] In July 1881 Pope Leo XIII, by the apostolic constitution Ex hac augusta, established the ecclesiastical province of Vrhbosna, which also contained Herzegovina, and appointed a residential bishop for the diocese of Mostar, to which he joined the ancient title of Duvno.
Paul VI references Leo's Romanos Pontifices, an apostolic constitution of May 1881 which defined the relationship between bishops and members of religious institutes.
After consultation with Sacred Congregation for the Evangelization of Peoples or Propagation of Faith, the Pope decreed that "in consideration of the merits which the Friars Minor of the Province of Herzegovina have secured for themselves, the Holy See accepts that it be taken as a general rule that half of the faithful of the diocese of Mostar-Duvno remain entrusted to the pastoral care of the same religious, while the other half entrusted to diocesan clergy.
It also confirmed Stephan László, bishop of Eisenstadt, as Apostolic visitor to Herzegovina, assisted by Vladimir Vlašić, S.J., rector of the inter-diocesan minor seminary of Zagreb.
However the parties noted that it was not possible for diocesan clergy to immediately assume their assignments due to "...acts of organised physical resistance, serious written and verbal threats, occupation of parochial Churches and houses, removal of parish registers and stamps.