Total War Attila replay. Historical battle of Dara 530 AD. Legendary.

In all my experience in Total war games, I find that I do well in defensive battles. That is why I decided to play this again but this time on Legendary difficulty.
This battle comes from the The Last Roman DLC pack for the game Total War Attila.
In AD 530, the Eastern Roman Empire and the Sassanid Empires are at war with the conflict not going the Eastern Roman Empire's way. In response, Emperor Justinian I of the Eastern Roman Empire dispatches the Roman general Belisarius to defend the town of Dara which is the Sassanid Empire's next target.