Miles O ' Brien ( mirror ) Miles " Smiley " O ' Brien was a slave who worked for the Klingon - Cardassian Alliance aboard station , but later became the leader of the Terran Resistance Forces who fought the Terran Rebellion . In 2370 , O ' Brien was working in the station ' s ore processing center , and had the slave classification " theta " , which was a relatively respected and privileged position . O ' Brien was also occasionally recruited to repair ' s raider when it was docked at the station . Sisko claimed he hated the name Miles , and instead nicknamed O ' Brien " Smiley " , despite of Smiley ' s lack of approval . He had a good reputation on the station for being an excellent " tinkerer and putterer " . When Smiley met a Julian Bashir from another universe in the ore processing center , he initially thought that Bashir ' s " wild " tales of his counterpart being Chief of Operations was simply a ruse to get him to help Bashir . However , Bashir ' s earnest attitude won him over , along with the realization that anything had to be better than his slavery to the Alliance . Smiley helped Bashir try to escape from the station , on the condition that he be taken along to the other side . However , when Captain Sisko also rejected Intendant ' authority , Smiley changed his mind and decided to join Sisko ' s crew , deciding that there was something worth staying for after all . ( ) When Captain Sisko was killed by the Alliance in early 2371 , Smiley took charge of the Terran Rebellion . In order to complete Sisko ' s last mission , he recruited Benjamin Sisko from the other universe to take the place of his deceased counterpart long enough to convince to leave the Alliance and start working for the Rebellion . ( ) While he was aboard Deep Space 9 , Smiley took the opportunity to download a large portion of the station ' s database , including the schematics for the . This information came in handy the next year , when the rebels managed to capture Terok Nor from the Alliance . Smiley used the stolen specifications to build the rebels ' own warship , which they also christened " Defiant " . However , with the Alliance about to launch a counterattack to recapture the station , Smiley once again recruited Sisko in order to help them finish construction of the " Defiant " in time . Smiley pilot ed the ISS " Defiant " during the Battle of Terok Nor , although he was replaced by Sisko partway through , because Sisko had greater experience flying the little warship . Following the successful conclusion of the battle , Smiley sent Sisko back home . ( ) In 2375 , Smiley was still in command of the rebellion on Terok Nor . He commanded the " Defiant " when it pursued ' s ship as it stole a cloaking device from the station , and later negotiated Regent ' s surrender and capture . ( ) Apocrypha . Prior to the establishment of the history of the televised mirror universe , a mirror version of O ' Brien appeared in the novel " Dark Mirror " , depicting a mirror universe in which the Terran Empire had survived well into the 24th century . That version of O ' Brien served as a conn officer aboard the ISS " Enterprise " ( ICC - 1701 - D ) from 2364 until at least 2367 . The " " novels feature General O ' Brien after " The Emperor ' s New Cloak " . During the " Star Trek Online " mission " Crack in the Mirror " , it is revealed that O ' Brien had a son named James who murdered him some time after 2375 . This is separate to the events in the novels .