Now I realize I might not ever be able to win any debate against any of you but I believe the two reasons for Rome's success were it's great organization skills and capable military leaders that stepped up every so often. It was proven through the Roman's biggest defeats that if they had a capable leader they might of been able to win those battles. In the battle of Cannae if C. Terentius Varro didn't lead the Roman forces down the from higher ground where they had the advantage he led them down to the plains where it forced L. Aemilius Paullus to fight Hannibal on his terrain, the flat surface, the Romans might of had a chance, maybe. There the Romans got crushed and if it weren't for Scipio Africanus who led the force which crushed Carthage, Rome might have been crushed herself. In the battle of Carrhae Marcus Crassus was a complete fool motivated by glory and which in the end he died. Now, no general really showed up to save him, yet his two highest surviving officers showed great bravery in the Roman retreat. And finally one of the other great roman defeats was at Teutoburg Forest, where Publius Quinctilius Varus made a lot of mistakes. Of course, the Roman Army came back under better command and punished the germans.
These three Roman defeats show how even the best armies can lose horribly if put under bad command and how if it weren't for good, capable generals who came along and helped defend Rome, we might not even be discussing anything much about Romans.
Now the greatest general i could never tell, but Marcus Trajanus is up there with Julius Caeser.