This was actually shot as a pilot for a prospective TV show, but it was passed on and shelved. Four years later, when stars Adam West and William Shatner had each reached a certain level of fame to get respectable ratings for the show - West was in the throes of Batman-mania from the success of his Batman (1966) series and Shatner was the star of Star Trek (1966) - it was released as a made-for-TV movie.
This was an unsold pilot re-creating the historic Battle of Issus (333 B.C.) in which Alexander the Great's Macedonian army met and defeated the much larger army of the Persian Empire.
The film was a pilot for a proposed TV series that never aired. It was originally telecast as an episode of the family anthology TV series Off to See the Wizard (1967).