Pity the poor biographer trying to compete with the novelist. A case in point: Virginia Rounding straining to evoke Catherine before she became great, when she was still Sophie Frederica Auguste of Amholt-Zerbst, one of those 300 or so 18th-century German principalities occupying what a Russian historian once called the “feudal anthill.”

Engaged to another provincial princeling, Karl Peter Ulrich, Duke of Holstein-Gottorp, Sophie had to negotiate her way through the intrigues of the Russian court, when Karl Peter became Emperor Peter III upon the death of Empress Elizabeth (daughter of Peter I, a.k.a. Peter the Great, and aunt of Peter III). I’ll spare you any more genealogy (Ms. Rounding provides a family tree) and cut to the scene where this backwater Lutheran pair is expected to make a royal coupling: “She was too immature to be able to have much understanding for her fiancé, who must also have been nervous and may have been avoiding her because he did not know how to behave with someone he was soon to marry.” Ms. Rounding is witty about the comedy of their courtship — all the more reason she should not indulge in must-have-beens. The future Peter III was a year younger than the 15-year-old Sophie and never did get over his preference for playing with toy soldiers. It took him quite a few years to consummate his marriage to Sophie.

Ms. Rounding is surprisingly tolerant of the oafish Peter, who drank too much and surrounded himself with German cronies, while Sophie transformed herself into Catherine, a devout Russian Orthodox ruler who learned about power from her lovers and steadily put distance between herself and her stupid mother, Princess Johanna Elizabeth of Holstein-Gottorp, a bumbling schemer eventually sent home in disgrace from the Russian court.

Ms. Rounding clearly admires Catherine, relying often on her subject’s writing to set the scene—although she also notes where Catherine seems to be exaggerating and self-serving. Catherine wasted little time getting rid of her husband Peter, who neglected to win the affections of his Russian subjects. She engineered a virtually bloodless coup, the only casualty being Peter himself. And she was remarkably generous to her husband’s mistress and other followers.

“Catherine the Great: Love, Sex, and Power” (St. Martin’s Press, 566 pages, $29.95) is not a political work or diplomatic history. The atmosphere of Catherine’s world counts more for Ms. Rounding. When Catherine came to St. Petersburg, for example, it was not yet a grand capital. Many of the buildings were wooden structures lacking the grandeur that would come to mark Catherine’s reign as a patron of the arts and “The Star of the North,” as Voltaire called her.

Ms. Rounding is unabashedly fascinated with the spectacle of monarchy. We are treated to extensive coverage of what it was like for royals on the road — all the servants, carriages, and paraphernalia required to swell an imperial progress. Similarly, Catherine’s coronation and other public events are reported in minute detail, as though broadcast on radio by a “color commentator.”

Catherine knew how to put on a good show, and Ms Rounding excels in burnishing her settings. What made Catherine so successful was her attention to detail even as she studied hard, reading Voltaire and other leading lights of the 18th century.

Catherine seems a strikingly modern figure in her ability to reinvent herself. That she was a woman meant that she was underestimated — fatally so by her own husband, but also by other men who thought she would rule only until her son Paul was of age. Hardly! Ms. Rounding demonstrates that Catherine always aspired to power.

Catherine put up with and savored it all — miscarriages, children by several lovers, the usual assortment of court schemers — and triumphed over all her rivals. Ms. Rounding is persuasive: Catherine the Great deserved her title.

But do not be misled by the subtitle. Ms. Rounding plays fair. She announces from the start that she wants to “put paid to the more salacious rumours which have sullied [Catherine’s] reputation so unjustly, even in her own lifetime but particularly since her death. That this most civilised of women should be known by most people only in relation to the infamous and entirely untrue ‘horse story’ is one of the great injustices of history.”

Well, I can think of a few greater injustices, but Ms. Rounding’s aggrieved tone is otherwise absent from her biography, which aims at showing how Catherine’s life unfolded “day by day.” The result is a biography told with great vigor and vividness.

crollyson@nysun.com