One of the three lost episodes remade is A Stripe for Frazer.
The episode, written by Jimmy Perry and David Croft, originally broadcast on Saturday, March 29, 1969. It was the fifth episode of the second series and fans say it was a biggie.
It was in this episode that Captain Mainwaring gets to wear his officer's hat for the first time, and we discover what happened when Sergeant Wilson jilted Mrs Pike at the altar.
It tells of the intense competition for a corporal's stripe as Private James Frazer, played by John Laurie, who died in 1980, vies with Lance Corporal Jones to win a little power over their colleagues.
After the show aired, the videotape was returned to the BBC engineering department where it would be wiped and new programmes recorded on top. A Stripe For Frazer was presumed lost until a fan came forward with a private collection of audio tapes in 2008, allowing an animated version to be made.
The new remakes are the first dramatised version since the originals were screened.
Dad's Army was broadcast on the BBC from 1968 to 1977, ran for nine series and was regularly being watched by 18 million viewers.