Since we're talking about generalship, why limit ourselves to the actual historical figures? We can learn as much about generalship from history as from fiction, poetry, etc...

So, to the running list of great generals I would add...

Sam Damon (of Once an Eagle fame)

Also,
Epaminondas,
Henry V
The Dead Germans (Rommel, Guderian, von Mellenthin, and Kesselring)
Sherman (the only guy who predicted the nature of the coming Civil War)
MacArthur
Arminius (defeated the Romans at the battle of Teutoburg Forest, holding the Romans at bay for centuries. As opposed to the exalted Boudica, who lost to Rome and left only ruin).