My first question would be, How this film get into a box set of sf films? You could stretch the definition of sf to include a Hercules film because of the fantasy elements, but this is a straight-up Roman gladiator film.
Filmed in Italy in 1964, this flick (originally called I Giganti di Roma) is one of the less well-known of the genre -- it doesn't even have a Wikipedia page.
The forces of Rome set out to defeat the Druids but discover that the Druids have a powerful secret weapon. Cladius Marcellus (played by Richard Harrison) leads a squad of Roman soldiers behind enemy lines to find and destroy this weapon.
Where's Russell Crowe when you need him?
There's just not much to say about this film. If you like this sort of thing, it's the sort of thing you'll like.
What's really interesting is that someone feels that star Richard Harrison is worthy of his own Wikipedia page, quite a substantial one in fact. Although almost unknown in his native USA, he began starring in Italian action films in the 1960s and had a long career in B-movies and developed a large European cult following. He made spaghetti westerns, as well as more sword and sandal epics, although oddly enough this film isn't listed on his Wiki page.
He also turned down the part of the Man With No Name in A Fistful of Dollars, and once said, "In my opinion, it is a death wish for an actor to be in too many B or should I say C movies. Maybe my greatest contribution to cinema was not doing A Fistful of Dollars, and recommending Clint for the part."
In the 1970s, the era of the spaghetti western ended, and Harrison began starring in exploitation films like Dig Your Grave, Friend...Sabata's Coming; The Godfather's Friend; You Can Do a Lot With Seven Women and Voodoo Baby (aka Black Orgasm). He even played American President Andrew Johnson in a 1982 Iranian production Hajji Washington.
His career took him to the Philippines in the 1980s were he made where a few really low budget action flicks, then to Hong Kong where he made one film for filmmaker Gordon Ho. However, Ho used Harrison's scenes over and over again in dozens of Ninja films like Cobra Vs. Ninja, Golden Ninja Warrior, and Diamond Nínja Force. Harrison now runs an electronics company called Gladiator Electronics.
I also discovered that sword and sandal films are properly referred to as peplums, which is Latin for the kind of tunic favoured by the costume departments because they were easy to make. So now we've both learned something. You learned what a peplum is, and I learned that I would rather have my skin flayed off with dull glass shards dipped in acid and rolled in lemon juice than watch another one.