At the Battle of Cannae, the Carthaginian general Hannibal (the guy with the Elephants) successfully defeated a numerically superior Roman army, by spreading out his line and attacking both flanks of the Roman army, enveloping it and restricting its ability to bring its number to bear.
It is regarded as one of the greatest tactical feats of antiquity and one of the greatest defeats of Rome. In fact, the defeat was so total that the Romans refused to engage him in open battle again. Forcing Hannibal into siege warfare for which he was ill-equipped.
So, if you wanted to wargame this battle how would you go about it?
The problem is that, at the time, Hannibal's tactics were unexpected. The Roman commander Varro, was impatient and arrogant, engaged too quickly and fell into Hannibal's trap. But a modern wargamer knows exactly what to expect from the Carthaginians, and wouldn't be stupid enough to let history repeat itself.
You could introduce rules requiring the Romans to deploy and engage as they did historically. Or at least to limit the tactical options. But then why re-fight the battle if both sides are forced into repeating the same behaviour.
Alternatively, both sides could be allowed to deploy and engage freely. But this puts the Carthaginian player at a significant disadvantage. One of the reasons Hannibal's triumph is so famous is that it was an against-the-odds victory against a numerically superior foe. Unfortunately, most wargamers are not Hannibal.
The above illustrates the difficulty of reworking historical battles into wargame scenarios. Many a great battle was won because of incompetence of one side, the extreme skill of another or just plain luck. All elements that are hard to rework into an interesting game for both sides (I don't think anyone's in favour of pitching incompetent players against skilled ones just for a laugh).
One interesting approach, might be to let a games master run the scenario, without the players knowing which battle they are re-fighting. Hand both players the resources of the generals and see how it develops. Of course, this doesn't help to resolve imbalances, like the Romans greater numbers at Cannae.
In the end, not all great battles make for great games.