We had this question come up last night:
From the rules, we know that you have to destroy all the figures in a commander's unit before you can attempt to capture them. However, it is unclear whether damage can be "rolled over" straight into capturing the commander, or if you have to resolve the attack, and finish it completely before you can begin a capture attempt.
In other words, say you have Rikard Karstark with 1 cavalry trooper left. The opponent attacks and gets 5 damage. 1 is absorbed by Rikard's Toughness. 1 takes out the additional cavalryman. Do you then move immediately into a "Capture" attack, and use the remaining damage to capture Rikard, or does the attack resolve and the excess damage is lost? (Then subsequent attacks could attempt to Capture him.)