Hehe, I just did the same in 268 BC of my newly-started Eperios campaign. Romani besegied my Capua with a fullstack of mainly Principes (6)with substantial amounts of Triarii (4) and some Hastati (2), Rorarii (3), Accensi (2), Roman Citizen Cavalry (2) and a General's Bodyguard.

I had three 40-men Illyrian cavalry, two 27-men Bodyguards, 80-man unit of Levy Phalangites, 2 100-men units of Illyrian Levies (the crappy spear ones), plus four 50-man Hoplitai Haploi. Basically a depleted Eperiote army with a bunch of cavalry. I still won, with pretty low casualties of 40 men, mostly from the pila that the Romans unleashed on me in the beginning.

Seriously, Roman are ridiculously easy to defeat. Those three units are now down to 26-31 men each with silver chevrons. Every battle of mine is a quick enemy charge at my extremely thin (two rows) ragged line of levies followed by my own generals and Illyrians charging at the backs of the engaged enemy infantry, routing all of them at once, routing full units from the first charge.

So anyway, I defeated the Romani Capuan expedition and suddenly I found an empty Roma. No units inside. Only a single unit of Principes blocking the road to the "Eternal" City. I quickly dispatched the units with my two general's bodyguards and entered Roma, unopposed. After which I promptly massacred the population It felt wrong, I still have guilt on my shoulders, but I needed the money to get me out of debt. Not to mention Capua, whom I forgot to massacre, has 11.000 population and the people are not happy, at 70% happiness on low tax level.