Springhaven — R.D. Blackmore

A sweeping novel of the Napoleonic Wars by the author of Lorna Doone.

Capt. Caryl Carne, half French and half English, has returned to the coastal town of Springhaven in Sussex, home to his ancestral castle, which now lies in ruins. In secret communication with the French, he plots to aid them with their planned invasion.

Meanwhile, the Englishman known as Captain Scuddy is taken prisoner in France, where he learns of Carne's treacherous scheme. What follows is a sprawling tale of war, suspense, and intrigue, in which both Vice-Admiral Nelson and Napoleon himself make appearances.
“The whole atmosphere is briskly naval, full of a healthy salt breeze and the movement and life of the ocean.” -- The Academy