War does not determine who is right - only who is left.
Bertrand Russell
Sorry, Yoda trumps all.
In all seriousness, I wanted to address the OP a little closer.
What is it that makes a great man?
Is a great man a conqueror?
Or is a great man a peace maker?
Or does he combine elements of both when it's appropriate to do so?
Now, I'm assuming here that you're working on some character and trying to figure out what makes him great. If that assumption is wrong, feel free to correct me.
What makes a D&D character great? The answer is a compelling story. It isn't whether he's a fighter or a lover. It's whether his story is engaging, and keeps bringing you back to the gaming table.
Perhaps his life's path covers both realms. Maybe he wanted a life of peace, but when the Torsian Horde killed his family, he vowed to fight against them until his dying day. Or, maybe he was a soldier, but divine revelation showed another path in his life, and he became a prophet of peace.
Throw in some character flaws and a path for character development, and you're on your way.
Sometimes a great man is one who has followers. Both conquerors and peacemakers have had them. Sometimes, a great man has no recognition. Maybe your character fights an unseen foe, and no one knows about his secret war.
Or maybe, what makes a character great is that he tries to do the right thing, despite insurmountable odds.
Hope that helps.