... when John VIII. became Pope there were among the Croatians a number of priests, Germans, and Greeks from various parts, who were anything but calculated to convert them.  According to the epistle which the Pope wrote to Muntimir, duke of Croatia, they were doing more harm than good, breaking the laws both of the Church and of God himself; and, as they were not subject to any recognised superior, could not be checked.  Muntimir is exhorted in the same letter to follow the examples of his forefathers, and to place himself under the spiritual direction of Methodius, archbishop of the neighbouring Pannonia.  Whatever effect this letter had upon Muntimir, it is certain that in 879 his successor, King Branimir, made his submission to the See of Rome... (Lives of the Popes, Mann, v.3, 1906)