"Pray, who were those men I saw here a moment ago? Roose Bolton, Rickard Karstark, Galbart and Robett Glover, the Greatjon, Heiman Tallhart...you might have given the command to any of them. Gods be good, you might even have sent Theon, though he would not be my choice."
"They are not Starks,” he said.
"They are men, Robb, seasoned in battle. You were fighting with wooden swords less than a year past."
-George R.R. Martin, A Game of Thrones

Before you take command in battle for yourself, you must practice and prepare. The rules for Battles of Westeros (PDF, 5.3 MB) are now on the support page!