XXXI.9 How Church properties were converted into fiefs
Fiscal assets should have had no other destination than to serve as presents which the kings could make to invite the Franks to new enterprises, which at the same time increased the fiscal assets ; and such was, as I have said, the spirit of the nation ; but the presents took another turn. We have a speech of Chilperic, grandson of Clovis, who was already complaining that these properties had almost all been given to the churches. “Our treasury has become poor,” he was saying, “our wealth has been transferred to the churches  ; no one reigns any more but the bishops : they live in grandeur, and we have disappeared.” 
That is why mayors, who dared not attack the lords, divested the churches ; and one of the reasons Pépin cited for entering Neustria was that he had been invited in by the ecclesiastics to halt the enterprises of the kings, which is to say the mayors, who were depriving the Church of all its possessions. 
The mayors of Austrasia, in other words the house of the Pépins, had treated the Church with more moderation than they had in Neustria and Burgundy ; and that is very clear from our chronicles,  where the monks never tire of admiring the devotion and liberality of the Pépins. They had themselves occupied the highest ranks in the Church. “A crow does not peck out the eyes of another crow,” as Chilperic would say to the bishops. 
Pépin subdued Neustria and Burgundy ; but having taken, to destroy the mayors and kings, the pretext of the oppression of the churches, he could no longer divest them without contradicting his title and revealing that he was mocking the nation. But the conquest of two great kingdoms and the destruction of the opposing party furnished him means enough to satisfy his captains.
Pépin made himself master of the monarchy by protecting the clergy ; Charles Martel his son could maintain himself only by oppressing it. This prince, seeing that a part of the royal properties and of the fiscal assets had been given for life or as property to the nobility, and that the clergy, receiving from the hands of the rich and the poor, had acquired a large share even of the allods, divested the churches ; and the fiefs of the earliest division no longer subsisting, he created the fiefs a second time.  He took the properties of the churches and the churches themselves for himself and for his captains, and put an end to a disease which, unlike ordinary disease, was all the easier to cure that it was extreme.