Miles O'Brien was born in September, 2328 in Killarney, Ireland, Earth.  In 2346 he enlisted in Starfleet and a year later was positioned on the U.S.S. Rutledge.  That same year, he fought in the Battle of Setlik III and was decorated for his deeds.  He was also reassigned to the position of Bridge Tactical Officer on the Rutledge.  He went on to serve on several different ships.
    In 2264 he was transferred to the U.S.S. Enterprise under Captain Jean-Luc Picard.  He was first assigned as a relief flight control officer in the command duty division but later was reassigned as a security officer in the operations division.  He was again reassigned at chief petty officer rank to be a transporter chief.  During his time on the Enterprise he married Keiko Ishikawa.
    In 2369 he accepted the position of chief of operations at Deep Space Nine under the command of then Commander Benjamin Sisko.
    At present he has a daughter, Molly O'Brien, and a son, Kirayoshi O'Brien.  He is still chief of operations aboard Deep Space Nine.