Littlejohn this Herculean assignment years later (quoted in Leonard Maltin's "Of Mice and Magic"): "I'd gotten excited about it and said, 'That's one of the ones I want to do,' and oh God, I was an idiot for volunteering. It was a staggering amount of work. There were a lot of shingles there!"

*Sourced

To corroborate Peet’s account; here’s a rather patronising inter-office memo from director Woolie Reitherman to Peet. Particularly noteworthy are the parallels: “Can you animate the picture?” (Walt) and “Remember you are not going to animate the picture” (Woolie)

Sources from Andreas Deja’s blog.