Lovestorm, by Barbara Benedict

Eager to escape her grandfather’s hatred, high-spirited young Katherine Farley agreed to marry Julian Warwick, a stranger from across the sea. Immediately he swept her away, setting sail for his home in South Carolina. On board ship, Katherine soon discovered that her new husband was not the foppish Julian, but Julian’s younger brother, Kit, the virile captain of a privateer whose mission was to prevent British soldiers and arms from reaching the embattled Colonies.

Though shocked at Kit’s deception, Katherine could not resist his fiery touch, giving her heart completely to the dashing impostor, though she feared he did not reciprocate her love.

But Charleston held even greater torment for Katherine, when she met the real Julian Warwick — and Rachel, Kit’s ravishing fiance!