Oh I understand. Clearly this is some Sun Tzu level shit.
When going in to war, it's important to 'cut ties' with the closest family members you have and send them away. Obviously no one will try to use their lives against you, or simply kill them out of malice, so no worries there. After all, they might be in danger if they stayed where your loyal troops could defend them. Clearly you should send them straight in to the arms of a duke that has, in front of your eyes, declared herself for your enemy's side. Because the commander of a medieval military force on the enemies side could have no incentive or malice to harm your loved ones in anyway.
And when it actually comes the fighting? Stay in your stationary castle with your incredibly mobile, hard to counter and perfect for hit and run air force and wait for a slow moving army. Don't harrass or test your slow moving enemy. It's the only logical move. Make sure to disband 90% of your loyal and expert soldiers too, because the 100 you left behind all secretly want to die as quickly and efficiently as possible.
OH! I nearly forgot. Anti air weaponry? yeah, your enemy probably won't use them against your air-only army. Dont expect them.
It's genius guys. Just absolute god damn genius.