Which preposition to use with ippolito

of Occurrences 2%

Towards the year 1504, the poet entered the service of the unworthy prince, Cardinal Ippolito of Este, brother of the new Duke of Ferrara, Alfonso the First.

at Occurrences 1%

The Pope sought to redress the disorder: he owed much to Ippolito at the time of his election to the Papacy, which was in a great measure achieved by his keen advocacy, so he sent him on embassies to the Emperor at Barcelona, and to the King of Naples, under promise of rich revenues.

Which preposition to use with  ippolito