Cabose... just no. The Spartans were from the Greek city-state of Sparta, and fought long before the Roman state even existed. The Spartan army never once fought with or against the Romans because the Romans came hundreds of years later. It's like cavemen fighting dinosaurs, it never happened. And yes it happens in the game Spartan: Total Warrior, but that is a GAME. It isn't serious history, the developers say that repeatedly.
SPARTANs are also the modified super soldiers in Bungie's Halo universe. They wear MJOLNIR armor and were originally created to crush rebellions from backwater planets against the human government, but when the Covenant arrived and started destroying those rebelling backwater planets, the SPARTANs were sent into action against them. Master Chief (a.k.a. John-117), is a SPARTAN, and there were 32 others still alive prior to the beginning of the first Halo game. In MP, you are just a SPARTAN, not any particular one, and definitely not Master Chief since he's off saving the universe.
