Cardinal Hosius, writing in the sixteenth century, admits that (credo)baptists were long persecuted by the RCC, and then by the 'Reformers' too:
"there shall be no faith more certain and true, than is the Anabaptists', seeing there be none now, or have been before time for the space of these thousand and two hundred years, who have been more cruelly punished, or that have more stoutly, steadfastly, cheerfully taken their punishment, yea or have offered themselves of their own accord to death, were it never so terrible and grievous. Yea in Saint Augustin his time, as he himself sayeth, there was a certain monstrous desire of death in them. . . . Neither was there such foolish hardy heretics in Saint Augustine his time only. For four hundred years ago, at what time St. Bernard lived, there were Anabaptists, which were no less prodigal to spend their life, then were the Donatists, some (saith he) did marvel that they were led to their deathe not only patiently but as it semed very frolic and merry.
...If you behold their cheerfulness in suffering persecutions, the Anabaptists run far before all other heretics. If you will have regard to the number, it is like that in multitude they would swarm above all other, if they were not grievously plagued and cut off with the knife of persecution. If you have an eye to the outward appearance of godliness, both the Lutherans and the Zwinglians must needs grant, that they far pass them.
...And surely how many so ever have written against this heresie, whether they were Catholics or Heretics, they were able to overthrow it not so much by the testimony of the scriptures, as by the authority of the Church."