50 years ago the creators of 'A Charlie Brown Christmas' thought it was terrible and would fail

Every year, millions of viewers count the "A Charlie Brown Christmas" special as part of their holiday tradition - a far cry from what its creators believed after watching the finished product 50 years ago.

"We thought we had ruined Charlie Brown," said the special's executive producer Lee Mendelson in a taped interview.

On Monday, ABC will celebrate the 50th anniversary of the popular "Peanuts" animation with a special at 8 p.m. and an airing of the program at 9 p.m. It's such a big deal, the US postal service issued a line of stamps for the anniversary.

But in 1965, Mendelson and then CBS (which owned the rights to the special) programming executive Fred Silverman believed they had made a terrible show and that it would air one night and they'd be done with it.

"We didn't think it worked," Mendelson explained. "We thought it was too slow. We didn't know what the network was going to think. And I took it back to New York and the network really didn't like it."

It was the first broadcast special to be made from the popular "Peanuts" comic strip. "Peanuts" creator Charles Schultz had just days to write it and with just six months to produce it, Mendelson was creating things out of thin air. Children without any acting experience voiced most of the characters, and Snoopy's utterings were actually provided by the director, Bill Melendez.

Silverman said of the network's take: "The general reaction was one of disappointment, that it didn't really translate as well as we thought it would."

But the special was already in the TV listings, so they had to air it. "[The network said,] 'Nice try. We'll put it on once and that will be it,'" Mendelson recalled.

To everyone's surprise, the show aired on December 9, 1965, and it was a hit. It earned a 49 audience share, which meant pretty much half of American households with TVs watched "A Charlie Brown Christmas." It was the second-most watched show that week, behind the very popular western series "Bonanza." And it ended up winning an Emmy for Outstanding Children's Program the next year and a Peabody Award.

 It has since aired every year since that first broadcast.

"I think we are all as overwhelmed today as were back then and that it keeps going on and keeps going on," Mendelson said.

Watch the interviews below: