She'S The Strongest Bride, But I'M Stronger In Night Battles: A Harem Chronicle Of Advancing Through Cunning Tactics (Manga) Vol. 1 - Singyougaku - Bog

In this Mature-rated isekai manga, an ordinary man becomes a military genius and the hottest lover in the realm--in another world! Compelled to marry a royal demoness and put to work--on the battlefield, and in her bedroom--Albert finds his new life in another world anything but peaceful. Yet thanks to his knowledge of Earth's history, Albert is able to launch a revolution, and is having a ball doing it alongside his sexy demon bride! ...