On Sunday, May 11, 1980, ABC premiered a Rankin/Bass movie, a two-hour J.R.R. Tolkien adaptation: The Return of the King.
The producers did The Hobbit in 1977 and enlisted another all-star cast for this follow-up. Wikipedia has the date wrong, by the way; listing its premiere as November 11, 1979.
By the way, remember a couple days ago when we talked about NBC's TV movies airing May 8 and May 9 1980 and how it promoted Capricorn One as 'coming soon"? Well, it WAS soon--May 11! Was it too confusing to just tell people "Sunday"?