I thought it was Stephen Boyd, Alec Guinness, Christopher Plummer and Gladiator Anthony Quayle, whose Gladiators fled the battle and were “decimated”.
The Fall of the Roman Empire (1964) - IMDb
Yes, I remember back that far...I like to compare those two movies.
Don't forget Maximinus Thrax, who should have been portrayed on screen by Andre the Giant. :^)