I mentioned Mike Duncan's History of Rome podcast before, but I thought I'd share with you guys the episodes of his show pertaining to each of the scenarios included with the game. They're in bite sized, 20-30 minute files, perfect for slapping on your Ipod while at work or study hall. These episodes should be really good primers for anyone who wants to know more details about the events covered in the game's included scenarios.
Enjoy!
Marius vs Sulla
http://en.wikipedia.org/wiki/Sulla%27s_first_civil_war
The Great Mithridatic War
http://en.wikipedia.org/wiki/Third_Mithridatic_War
The Spartacus Revolt
http://en.wikipedia.org/wiki/Third_Servile_War
The Roman Civil War
http://en.wikipedia.org/wiki/Caesar%27s_Civil_War
Year of the Four Emperors
http://en.wikipedia.org/wiki/Year_of_the_Four_Emperors
Septimius Severus
http://en.wikipedia.org/wiki/Year_of_the_Five_Emperors
EDIT - Put in some wiki links for anyone who'd rather read about the events than listen to the podcasts.