DYNASTY WARRIORS 9 Empires

First of all, play on Very Easy or Easy difficulty.

Second, I recommend changing your Military Unit to Combat Medic, so that you get passive health regeneration. You will take some hits, and this is the easiest way to recover. From your Throne Room/Political Commands menu, press to go to your Info menu, go to Player Info, and go to Military Unit Settings. The Combat Medic option is unlocked pretty early in the normal course of playing a campaign, either by leveling up your stats or recruiting certain officers.

Fighting a defensive battle is easiest. Back in your Political Commands menu (), use to toggle your display to see which of your neighbours has the fewest officers, and bait them into attacking by using Human Affairs>Change Position to draw your officers down to 1 in an adjacent province (each province must have at least 1 officer stationed in it). It does NOT have to be your main chacter - you will always be given the option to use your main character in a defensive battle, regardless of where your main character is actually stationed. Just make sure that when the attack comes, you remove the local officer from your defensive forces by pressing on their name.

You will be notified several months/turns before the attack comes. Use this time to strengthen your defenses (Military Affairs>Upgrade defense/fortress from Political Commands menu). I think it makes your castle more resistant to siege weapons, but I'm not sure.

During a defensive battle, the time limit is on your side - run out the clock and you win. Focus on running interference on the enemies' siege weapons - if they can't penetrate your castle, they can't capture your main base. Also, don't worry about your troop numbers - if/when they drop to zero, your bases will still spawn defenders, so you will never be totally on your own.

Obviously all of this requires that you play as a Ruler. You don't have this kind of stategic latitude as an Officer.

Finally, I know that this game (like every other Dynasty Warriors: Empires game) is a UI nightmare (I love them anyway). If you need any additional help with navigating the menus, please post a comment.