Which preposition to use with unfrock

with Occurrences 1%

It was a pretty romanceall those noble councillors, trembling from fear of the extinction of this most ancient and princely house, framing humble petitions to the Holy Father; the youthful monk, leaving the tranquil solitude of his island sanctuary, unfrocked with honor by a Pope's decree, to don the crimson robe of senator and wed the daughter of the Doge!

Which preposition to use with  unfrock