I remember reading this manga/manhwa (I forgot which) on, probably, MangaRock, but can't remember the name of it, or even find it! And it's really frustrating. I remember the genres should be: josei, romance, historical. I think it was based on a novel, probably a Korean novel? And the cover of the mahwa/manga is the face of the male lead, with dark blue/black, short hair, wearing knight uniform, standing straight with stoic face.

The first chapter, in my limited memory, went like this: The story was set in some kinda past European era. The male lead was a knight in some kingdom who one day led a ride to female lead's kingdom and killed almost all of the people in the female lead's kingdom. Eventhough very cruel, somehow, he spared female lead's life and she became a slave instead. But he did so not because he liked or loved her, there was some kinda secret intention to let her alive, for the time being at least.

Anybody know the title of this? Any help would be greatly appreciated! Thanks in advance!

Kind of reminded me of Beatrice
But not everything matches