Rakuin no Monshou - Volume 1, Chapter 5: Princess Vileena

... obstructed view of plains was spread out. If Mephius actually wanted to cross the border and invade, Zaim Fortress was considered to be its biggest hurdle.

Ryucown had made it surrender in the blink of an eye and turned it into his own stronghold. It could be he had the help of traitors, but it could also be that the people at Zaim Fortress never intended to turn their blades toward Ryucown, because he was a Garberan to begin with.

And besides...

Maybe he secretly got ass ...