Looking for a manhwa

I forgot the title but the cover page was a female knight? I guess (and no its not emperor and the female knigt).The story was that the mc before she got reincarnated she was once a battle hardened soldier. She was betrayed by her allies and was killed. When she woke up she was in a fantasy world and yada yada. The prince made her a knight even making her the leader of a special untlit specializing in assasination if im not mistaken.