This exceptional historian is one of those few judaics who has rejected Holy Church out of ignorance as oppossed to hostility. His three works that I have read are

1--Kidnapping Of Edgardo Mortara
2--Popes Against the Judaics
3--Prisoner Of The Vatican.

His father was a friend of Eugenio Zolli and defended the latter from reproaches by his kindred upon his conversion(although some such as myself suspect that the rabbi may have been a Marrano).

Mr Kertzer is unique in that he is so sure of himself, that he is not afraid to give the Catholic side of whatever issue he is writing about and his books are full of info especially about papal affairs beg w/ about Pius IX and through Pius XI generally.

Highly recommended. Ciao

 

You will find this author most facinating. His works will answer your question or I would try but am not quite sure what you are asking. Pius IX and Fr. Mortara were very close.