This is driving me nuts, honestly. I can't for the life of me remember what this manga was, but I can give you what I do remember.

It's about a Prince who's all for peaceful methods of negotiation. He's a cunning bastard who manages to bluff his way out of an attack by a foreign war general (a girl, I think?). He likes to do stupid things like flip girls' skirts and spy on baths or something.

When the country gets invaded, he sends all the townspeople to a festival or something so that they'll be out of harm's way when the castle is stormed.

I think that's all I can remember? Any help would be appreciated, thanks!

Yes, that's it, thank you so much!