Which preposition to use with oligarchs

of Occurrences 2%

On pretence of these disagreements he loaded some of the principal citizens, the oligarchs of the republic, with chains and sent them to Moscow.

of Occurrences 1%

I have no doubt that in this petition more is meant than meets the ear; that the Oligarchs of Bern, as well as the Ultras of France, have a share in it, and that it may be considered not so much as an attempt to compel the Canton to refuse asylum to these exiles, as to excite the Great Powers to enforce the abolition of the independence of Vaud, and to replace it under the dominion and authority of the Canton of Bern.

Which preposition to use with  oligarchs