Corporal Gerald Mullen was a character made a single appearance in the Season 10 episode of the CBS-TV series M*A*S*H titled "Identity Crisis". The part of Corporal Mullen is played in the episode by actor Joe Pantoliano.
About Cpl. Mullen[]
When Cpl. Mullen, an infantry man who arrived with the other wounded in his unit, and who's really Josh Levin making his confession to Mulcahy, as he decided took on his comrade's dogtags after he was killed in their foxhole by artillery, in trying to get rotated and discharged back to the U.S..
Mulcahy has a seemingly arduous task in trying to convince Mullen, who is dead set on trying to make it back home stateside, even if it means using the name of his fellow soldier and fighting buddy, and running the risk of being caught by the authorities and getting convicted of desertion.
Nothing seems to work in Father Mulcahy's attempt to try to appeal to Mullen's conscience, which has been nagging at him already since he began his identity ruse, concerning what he's attempting to get away with, until Mulcahy receives a letter from Levin's family saying how much they miss him and were looking forward to the day he returned home so that they could greet him. This makes Mullen change his mind about pulling the identity ruse, as he, with the father's help, is able to reveal his true identity discreetly to Col. Potter, as well as the true identity of the person whose dog tags he had in his possession, Levin's, as he hands them over, and returns to his unit after his wounds are completely healed.