Which preposition to use with phanariot

in Occurrences 1%

On March 6 the 'Philikì Hetairia' at Odessa had opened its own operations in grandiose style by sending a filibustering expedition across the Russo-Turkish frontier under command of Prince Alexander Hypsilantis, a Phanariot in the Russian service.

Which preposition to use with  phanariot