I'm sorry for this image being in black-and-white, but it's the only one I could find on the internet that was large enough. This is a scan from the laserdisc release of Horus, which Nausicaa.net so graciously posted. I am thankful that they continue to be so useful.
In any case, this is the poster for Horus, Prince of the Sun. Toei really knew how to make movie posters, even though they had no idea what to think of this one. Sometimes, I think Toei still doesn't get Horus.
If you really want to understand the context of that era, just go to YouTube and watch clips of the Toei Doga feature films and tv shows. It's so easy for us to understand Horus today, after it blazed the trail for 40 years of progressive, adult anime. But in the 1960s? Good Lord, this movie was the Slayer of its day. Still is.