There is a wizard who captures and imprisons the lord of a castle and threatens to kill him if his men don't surrender his castle to a griffin. They agree to the terms and leave the castle, allowing the griffin to move in. Just wondering how does surrendering a castle actually work historically? Is it just a case of the surrendered people packing up their things and leaving and the victorious people moving in with their things, or in this case a griffin, or is there more to it than that? I know it's probably mundane and trivial to go into for a story but I want to add these details into my story.