"Raise de Kekkonshitekuremasu ka" to Chikatta Buka ga, Gensei de wa Toshiue no Kishi Danchou-sama ni Natteite, Hontouni Kekkon wo Semarareteiru Ken

The young lady Livia is plagued by nightmares of being a captain caught in a losing battle, seeing her soldiers die in front of her eyes. Then one day, at a party held at the royal palace, she was suddenly approached by Claudio, the handsome knight-captain. That was when Livia's memories of her previous life came back to her. Livia and Claudio's previous lives were that of a female captain and her subordinate. As he laid dying in her arms, Livia had promised to marry him in their next life! Back to the present, Claudio immediately proposes marriage to Livia!?

(Source: Comic Brise, translated)