Colonel Çelebi was in charge of a Turkish prison in Constantinople in 1914.
Çelebi worked closely with German agent Gerold Rösler. They were concerned about an artefact that had been discovered by Maurice Bernard and stolen by British agents.
When the Seventh Doctor was taken to the prison, he managed to convince Çelebi and Rösler of the artefact's danger. They assisted him in recovering it. (PROSE: Ante Bellum)