General George Casey was a MACO officer during the 22nd century.
Captain Jonathan Archer requested and received a MACO detatchment to be stationed aboard the Enterprise from General Casey before their mission to the Delphic Expanse. (ENT episode: "The Expanse")
General Casey also attended meetings on the formation of the Coalition of Planets. (ENT novel: The Good That Men Do)
During the Earth-Romulan War, Casey attended multiple meeting on Earth including those of the Coalition Security Council, meetings with Starfleet Admirals Sam Gardner and Gregory Black, and the meeting at Prime Minister Nathan Samuels's office at which Samuels announced the end of production of the NX-class in favor of the Daedalus-class. (ENT novel: Beneath the Raptor's Wing)
Casey (General) article at Memory Alpha, the wiki for canon Star Trek.