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.
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).
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.