They say that behind every great man is a great woman. “Napoleon,” Ridley Scott’s clamorously eventful but oddly desultory new epic, wrings its own variation on that idea: Here is a man whose love for a woman fuels and finally destroys his delusions of greatness. He, of course, is Napoleon Bonaparte, played by Joaquin Phoenix with a bicorn hat, a dyspeptic grimace and an unshakable air of post-“Joker,” post-“Beau Is Afraid” tragic clownery. She is Joséphine de Beauharnais, the glittering-eyed widow who will reign at Napoleon’s side for a spell as empress of France, and who is infused with quietly mesmerizing gravity by Vanessa Kirby.

“You are nothing without me,” Napoleon says, infuriated by reports that Joséphine has taken a lover. A few beats later, she seizes the upper hand, sealing a kinky contract of mutual need and ambition that will bind them long after they’ve been dethroned. For now, they conspire to rule over a fractious post-revolutionary France, and also to transform this lavish palatial drama and sinewy war epic into a veritable anti-romantic comedy. Their marriage is a mess of impromptu food fights, garish masquerade balls and frenzied bouts of eye-contact-free sex: Behind many a woman, it seems, thrusts a not-so-great man.

One of the movie’s fitfully tossed-off insights is that Napoleon’s grunting awkwardness in the bedroom and his tactical genius on the battlefield are expressions of the same intense desire — for dominion, conquest and a permanent place in history. Mission accomplished, bien sûr. (That’s almost more French than there is in the movie, a few soundtrack chansons aside.)

And yet the aim of “Napoleon,” as written by David Scarpa (“All the Money in the World”), is to puncture rather than inflate its subject’s mystique, which still clings to him centuries after his ignominious defeat and death. It means to expose the hollowness of Napoleon’s lust for power, to treat this Corsican outsider’s ascent into the upper echelons of French politics as a spectacularly bad joke — and to ensure that the thousands of casualties he left in his wake, from Toulon and Austerlitz to Borodino and Waterloo, catch in your throat like the cruelest of punchlines.

To heap contempt on one of history’s most iconic megalomaniacs is an entirely defensible artistic gameplan. Given how often this particular figure has overwhelmed great filmmakers in the past — among them Stanley Kubrick, who famously abandoned his storied Napoleon opus in the ’70s, and Abel Gance, whose butchered-and-restored “Napoleon” (1927) remains one of the tarnished masterworks of the silent era — there’s something to be said for a dryly efficient hit job from a craftsman of Scott’s prolific, unfussy Hollywood caliber. Funnily enough, though, his “Napoleon” might have actually benefited from a bit more fuss, a lot more political-historical insight and a less constipated visual style. (Scott’s stormy grays, muddy browns and sunburnt ochres are getting oppressive in their digital dreariness.) Its glimmers of comic rage and generous helpings of battlefield carnage, though patchily entertaining on their own, never coalesce into a coherent reason for being.

Phoenix, you might well argue, is reason enough. The movie does signal its darkly comedic aims from the moment we first see the actor’s gnomic man-child frown, which by now is a ready signifier of emotional and psychological deficiency. His Napoleon is introduced, in the first of the script’s unapologetic liberties, as a spectator at the guillotining of Marie Antoinette (Catherine Walker). The sight of the queen’s bloody, vegetable-pelted head being hoisted aloft instills in Napoleon a fervent commitment to anti-royalist ideals, at least until he crowns himself emperor some years later. It also anticipates a remarkable, nearly wordless scene in which he comes face-to-face with a much older dead monarch. In a rare moment of introspection, Napoleon sees, in an Egyptian pharaoh’s carefully mummified remains, a glimpse of his own future.

For the most part, “Napoleon” plunges noisily ahead, into a thicket of sly political maneuvers, clumsy rebellions, powdered faces, clashing accents and a few authentically thrilling battle sequences. Robespierre falls and Napoleon rises, though at one point he actually falls mid-rise, tumbling down a set of stairs just as he and his brother, Lucien (Matthew Needham), are staging their 1799 coup. Napoleon ascends through shrewdness and dumb luck, taking advantage of anti-royalist sentiment one minute and crowning himself emperor the next. (There’s a nice throwaway shot of the artist Jacques-Louis David, painting the coronation in all its red-cloaked, gold-leafed splendor.)

Through it all, Napoleon’s military genius is so peerless and unquestioned that Scott, regrettably, doesn’t feel compelled to unpack it. We’re meant to take it on faith when Napoleon alone determines how to take out the Anglo-Spanish fleet at Toulon with their own cannons. Or how, in the movie’s most visually and musically arresting sequence, to send the Russian and Austrian troops at Austerlitz to a bloody, watery grave. To his credit, Scott possesses his own brand of military genius, cinematically speaking; he can make spatially coherent sense of bayonet-wielding army formations in a way that few other studio filmmakers can, and he never stops visualizing new forms of splattery payoff. Old ones, too: When Napoleon’s pony gets hit by a cannonball head-on, the exploding entrails suggest an “Alien” chestburster homage.

Your mind will soon drift toward other Scott touchstones. Napoleon’s slithery courtship of Joséphine and ensuing battle of domestic wits call to mind the firelit power plays of “The Last Duel,” the director’s superior recent foray into French history. And there’s “Gladiator,” of course, in which Phoenix sulked up a storm as the Roman emperor Commodus, a performance that feels, in retrospect, like a petulant warm-up act for this movie. Between “Napoleon” and his forthcoming “Gladiator” sequel, Scott seems to be enjoying his return to the vein of historical filmmaking that launched his career with 1977’s “The Duellists.” Notably, though, nearly all his movies from the past decade, including “The Counselor,” “All the Money in the World” and, yes, “House of Gucci,” seem to spring from the same coldly unsentimental worldview, marked by a dim view of the human species and a grim fascination with the trappings of power.

Scott knows that people are awful in pretty much every era, and Phoenix’s Napoleon, of course, is a prime example. He is asinine, hypocritical and blind to his shortcomings. He dozes off mid-conversation, putting the “nap” in “Napoleon.” He treats his troops abominably, whether he’s deserting them in Egypt, condemning them to a death march through a Russian winter or sending them into the hopeless onslaught of Waterloo. He cheats on his cheating wife and over-indulges his appetites (“Destiny has brought me this lamb chop!” he declares, in one of the line readings of the year). The movie’s most meaningful recurring image is not of Napoleon commanding his troops, but rather of Napoleon gorging himself on food and drink, often at diplomatic meetings with foreign frenemies like Alexander I (Édouard Philipponnat) or Francis I (Miles Jupp). None of them can stand to be in his company.

Really, Napoleon just wants to be liked — and, in the case of Joséphine, loved. Their fascinatingly mercurial relationship lends the movie what structure it has, establishing a kind of combative dialectic between Napoleon’s personal and professional battles. When he and Joséphine are together, sometimes butting heads and sometimes collapsing into a strangely sincere tenderness, you catch glimpses of the epic romantic subversion that Scott may have been after. You hear it, too, in the sparkling piano chords of Dario Marianelli’s 2005 “Pride & Prejudice” score, repurposed in an Austen-tatious musical gesture that adds a touch of poignance to the characters’ looming tragedy: Joséphine is Napoleon’s most meaningful and elusive conquest, and she is destined to precede him in exile.

There is genuine comedy here and also a real measure of pathos. Too often, though, “Napoleon’s” withering condemnation of its subject feels less like a meaningful conclusion than a narrative dodge, a convenient way to sidestep a more trenchant, complicated look at Napoleon’s political legacy. It’s as if Scott were content to ridicule what he would rather not explore. People are awful; what more needs to be said, examined or contextualized? The conniving French diplomat Talleyrand (Paul Rhys) is awful. Napoleon’s mother (Sinéad Cusack) is awful, never more so than when Joséphine fails to produce an heir. The politician Paul Barras isn’t too awful by comparison, though awful more or less describes the waste of an actor as good as Tahar Rahim in a role this underimagined.

It’s often been said, given Scott’s skills as a superb visual craftsman and cinematic logician, that he’s only ever as good as his material — a reductive formulation that happens to be true in this instance. But it’s also true that, not for the first time with a Scott picture, the theatrical version is just a teaser for what’s to come. A four-hour “Napoleon” will stream on Apple TV+ at an unspecified date and, without judging it sight unseen, it seems reasonable to hope that it presents a richer, more cohesive and expansive vision of the story. Behind every so-so movie, after all, is a potentially great director’s cut.