beta
It’s about a girl disguise as a boy. I remember a handsome duke or something pick her up at a battlefield after some war. Her hair is white or silver. She lied about her family background and begged to the duke to take her.
The story description bears similarities to "The Villainess's Blind Date Is Too Perfect", where a female lead disguises herself as a man to become a knight and meets a duke on a battlefield.
Another potential match is "Undercover Empress", which features a female lead cross-dressing as a man in a military setting.
The description of a silver-haired girl disguising herself as a boy is common in the otome isekai genre, similar to characters in "I Choose the Emperor Ending".
Google gave this
Now that’s what you call a plot twist