I'm thinking that it's extremely unfortunate, from the perspective of this film or of those who would like to enjoy this film, that Jacques Tourneur seems to have departed from the production rather early. Certainly the pace of the film is completely dead in the water and the direction is more the listless early style of Mario Bava, who was uncredited for his direction of this film. Bava excelled when he was able to put aside plot and character and just focus on atmosphere, but this film did not allow him to do that. Instead it features many dialog scenes and a rather dull political story that Bava is unable to make digestible. The action scenes are fairly good towards the end, and there are some nice shots with the classic Bava lighting. That's about it.
Steve Reeves is our hero, this time appearing (as he did 3 years early in his debut in Ed Wood's "Jailbait") sans beard. He plays Phillipides, an Olympic champion caught up in the Greco-Persian war. He's in love with blonde Andromeda (Mylène Demongeot), whose father Creuso (Ivo Garrani) is part of an aristocratic plot to overthrow Athens' democracy and replace it with a Persian puppet government.
The first half of the film is basically setting up the romance and the war, and then in the second half you mostly see Steve Reeves running for what seems like 15 minutes, and then a huge naval battle with some interesting underwater photography.
Only a few of the shots in the film seem to bear any mark of Tourneur's style, such as the one that shows the Persian King Darius (Daniele Vargas) framed against his legions of soldiers in extreme closeup to contrast with the background. My guess personally is that Bava directed most of this film. It is a dull film even compared to Bava's Hercules films with Reeves.