"The Defining Chapter," declares the poster for Jackson's last Middle Earth movie, The Hobbit: The Battle of the Five Armies. In the sense that "definition" means clarity this claim is demonstrably wrong, for this movie is as muddled as you have heard: character motivation and identity a mess, narrative logic and consecutiveness hit-and-miss, emotional through-line clumsy and unengaging. Still, there's the related sense of "definition" as "expressing the essential nature of something," and where that is concerned the poster is much closer to the truth. Hobbit 3 is like Hobbit 2, but more so—a special effects splurge of weightless, affectless fighting and running around. Frankly the whole trilogy has proved less J.R.R. and more C.G.I. Tolkien.

The pre-credit sequence is a James-Bond-style self-contained set-piece. The dragon, Benedict Cumbersmaug, sets Laketown on fire, and movie touches briefly on one of what for want of a better word I'm going to call its main themes, viz. political leaders are untrustworthy types, fundamentally uninterested in the welfare of their people. In this case it's the Master of Laketown. Played by Stephen Fry with characteristically one-note Stephen-Fryness, he loads a barge with treasure and flees coward-fashion as his town burns. For heroism we have to look to Bard the Bowman, a man whose pronounced Welsh accent would be less incongruous if the rest of Laketown didn't speak generic Cockney. Bard climbs a clock-tower with a quiver full of arrows and fires volley after volley at the Wyrm. In the first draft of this review I inserted a "How Green Is My Volley?" joke at this point, but on reflection I think we're all better off without that. Of course his shots all bounce off the dragon hide, until, arrowless, his bow broken, Bard's young son pops up carrying a gigantic metal shaft. With the same bowstring, somehow rigging the two halves of his broken bow and using the boy—absurdly—as an arrow rest, Bard shoots this last shot. Now, the requirement that momentum be conserved means that any given bowstring can propel a lighter arrow faster or a heavier arrow more slowly. Somehow, though, this shaft hurtles with increased force and celerity, and Smaug is Cumberslain. Who knows how the laws of physics were thereby circumvented? Perhaps: magic. The prologue then pays off this early, minor iteration of its main theme by having Stephen Fry squished by the falling dragon corpse.

The main body of the movie is disposed into two sections, though these relate very uncomfortably to one another. In the first Thorin is afflicted by "dragon sickness" and becomes obsessed with the magic jewel Arkenstone, paranoid that his fellow dwarfs have betrayed him. He breaks his word with respect to helping the now homeless Laketowners, walls up the entrance to Erebor and generally goes to the bad. This is the movie's major key iteration of its main theme, and is underscored when the Elf King Thranduil rides up on an elk with a troop of gold-armored elvish warriors. It is not clear to me why a tree elf considers an elk an appropriate mount, or indeed what the elk—a beast surely more associated with tundra and open-grasslands—was doing in Mirkwood to begin with. But Hobbit 2 has already established that Thranduil is an example of the main theme: a monarch whose disconnect from reality and closed-borders policy has already been established as short-sighted abdication of the responsibilities of leadership in the face of the reappearance of Sauron. Here we see more of his ill-judged whim-of iron leadership. His "motivation" is that Smaug's horde contains a certain necklace he prizes, a flimsy enough pretext for war that the film never properly explains or unpacks. Bard, now de facto leader of the Laketowners, makes an alliance with the elves in the hope of compelling Thorin to honor his word, and give his homeless people the financial wherewithal to rebuild. Dragon-mad Thorin is implacable, and war seems inevitable.

Gandalf shows up, having escaped from his imprisonment by Sauron via set of narrative daftnesses too dispiriting to list here. Thranduil demonstrates again how ill-fitted he is to kingship by ostentatiously ignoring Gandalf's warning about a huge orc army, just over the brow of the hill. It seems war between dwarfs and elves/men is imminent. At this point Billy Connolly rides in astride a giant pig: a sentence which in almost any other context would be cause to give up writing the review altogether and instead head off to the pub, but which here strikes a note almost of sanity. Connolly is playing the dwarf king Dáin Ironfoot, and he has brought an army with him. The first half of the movie ends with these four armies arrayed against one another.

The transition into the second half of the movie is so jarringly abrupt one might almost suspect Jackson and his scriptwriting team of taking the piss. The orc army rocks up, just as Gandalf warned they would. Whilst the four forces were squaring off, Azog somehow managed to erect a command centre on top of a nearby mountain, in plain view of the battlefield and complete with a gigantic semaphore flag scaffold, and nobody noticed. I'm going to repeat that: and nobody noticed. From this eminence Azog then delivers his fifth army to the battlefield via tunnels specially dug by rock-chewing cousins of Dune's Sandworms. Titantic worms dig out tunnels a few hundred yards from Erebor and thousands of orcs swarm forth. As to why Azog didn’t have his titanic worms come up underneath the elvish/mannish/dwarfish armies and finish them off—or why he didn’t detour past the battlefield altogether, have then tunnel straight into Erebor, snaffle all the gold and carry it away . . . well these profound and puzzling questions are not addressed by the film. Also unclear is where the worms go once they've dug out the tunnels. What is clear is that the orcs' arrival bends the movie into a wholly new and tortuously implausibly shape.

The first volte face is that the dwarfish and elvish/mannish armies immediately forget their mutual enmity and coordinate to fight the orcs—coordinate, in fact, with the kind of precision it would surely take months of Bob Fosse coaching to bring about. The very first maneuver involves the dwarfs locking shields into a long testudo wall, and the elves leaping over this in unison to surprise the advancing orcs. The second about-turn is that Thorin abruptly cures himself of the dragon sickness (by, it seems, standing on a huge golden floor having a hard think about things). Newly heroic, he leads his troops into battle. There's a long interlude of CGI hewing and hacking, in which gigantic orcish warriors in armor made from slabs of pig iron prove ridiculously vulnerable to the swordplay of child-sized dwarfs wearing not very much. Still, our four forces (Thranduil's elves, Bard's men, Thorin's dwarfs and Dáin's larger dwarfish army) are hugely outnumbered by the orcs, and things look grim. Their response is the strategically jejune one of "cutting off the head of the snake," viz. ascending the eminence from which Azog is directing his armies via semaphore and killing him, thus making all the remaining orcs, I don't know, evaporate or convert on masse to Quakerism or something. To reach this height Thorin, Fili, Kili, Stabbi, Garoti and Dori the Explorer (I confess to being vague about the actual names) mount certain giant armored war rams that are standing nearby. From whence these rams came, why nobody else was using them, how they are able to leap up a sheer cliff: I regret to say I simply do not know.

Meanwhile, Legolas (looking spookily rather older than he does in the set-60-years-later Lord of the Rings films) and the she-elf Tauriel have been scouting the northlands. They discover an orc fortress, built in neo-Brutalist style out of angular slabs of concrete like a 1950s power station. As they watch this structure disgorges a whole new goblin army, headed by Bolg and preceded by a flock of screeching war-bats ("they are bred," Legolas tells Tauriel, "for one purpose only . . ." and you can almost see Orlando Bloom counting inwardly one-onethousand, two-onethousand, three-onethousand, before completing the line: " . . . war!"). These bats have almost no part to play in the battle, beyond screeching and flapping about, which makes me suspect that they were actually bred for one purpose only . . . CGI spectacle. That said, Legolas does grab a leg-o'-bat at one point, and use it for a leg-up, fast. Otherwise, like the rock-chewing worms and some nifty giant trolls with giant catapults backpacks, these beasts are to be gawked at briefly and forgotten about.

With the arrival of Bolg we're now dealing, by my reckoning, with six armies; but the more pressing concern is that Bolg's army will arrive first at Ravenhill and so surprise Thorin and his companions, including Tauriel's love interest Kili. So she hurries up the steep slope, with Legolas close behind. What follows is an interminable sequence of single combat scenes between Bolg and Tauriel, Bolg and Kili, Azog and Thorin and Legolas and Bolg. On and on it goes. Just when you think one of these parties is dead, s/he leaps up again and the single-combatting continues, like a video-game sword-fight version of those irritating candles waggish people buy for birthday cakes that, blown out, persistently re-light themselves. Bolg's army, meanwhile, are pouring into the valley and turning the tide of war.

It's at this point that an army of eagles arrives (so: seven armies?), giving the audience a two second glimpse of Radagast the Brown and a three second cameo by Beorn, sky-diving down to turn into a bear on the way. The eagles possess the ability to rake through whole battalions knocking them down with their talons like skittles (a skill they presumably lose in the later-set movies), and so the battle is decided. Legolas finally disposes of Bolg; and Thorin kills Azog, receiving a mortal wound in the process. The dwarfish king then has a fifty-minute death scene, expiring in Bilbo's arms in such a manner as to show how apt is his full name of Thorin Woodenactor. Nothing remains except some too-abrupt sequences of Bilbo returning to the Shire.

Given that this movie is more tightly, or at least more conventionally structured than either the weirdly bloated and misshapen first two, it's surprising that it works so much less well. It's almost as if it was the bloat and odd shape that redeemed Hobbits 1 and 2 from the mere dreariness of, in effect, watching somebody else play a video game. Too little is made of Bilbo's possession of the ring, except for one sequence when he wears it to slip through the battle and warn Thorin. Earlier films set up expectation of pay-off from the fact that the hobbit was keeping the possession of the ring secret from Gandalf, but in a bafflingly throwaway moment at the end of the movie it turns out that Gandalf knew all about it all along. Frankly, Jackson fluffs the significance of this artefact; for it has no rôle in this movie except to gesture forward to the Lord of the Rings trilogy. And, sadly, the film is full of this: Bilbo being given the mithril shirt for no reason (it doesn't figure in the actual battle at all) except that we know he later gives it to Frodo. Similarly, Saruman growling "leave Sauron to me," after Galadriel has—crazily—magicked The Evil One away into "the east," like Robin Williams's genie baseball-pitching the lamp containing Jaffar over the horizon at the end of Aladdin. The most egregious example of all comes at the end: Legolas, apparently heartbroken (it's hard to tell, his face is so mask-like) at the realization that Tauriel can never love him, is instructed by Thranduil to "seek out the ranger in the north who is known as Strider" but whose "true name you will have to find out for yourself," because "you two will become best buddies in the follow-up adventure and we need to lay that groundwork here. For the fans—for the fans, you see." And so, accompanied by the cracked-bell chime of this thuddingly over-literal foreshadowing, Legolas legs it at last.

Perhaps it is a mistake to judge this sort of text by such old-fashioned conceits as "character," "story," "coherence" and so on. We might prefer to judge it as an exercise in the visual spectacular, which approach certainly offers us more by way of satisfactions; but important though Weta have been in the development of special effects many of the shots here have an airless, waxy, artificial feel to them. Or maybe it would be better to think of this movie as a species of ballet. Once upon a time, people would queue outside the cinema to watch Ginger Rogers and Fred Astaire disport themselves to music in ways that foregrounded their almost godlike grace, an elegance of motion far beyond mortals like us. Now we queue to see Orlando Bloom, or rather his CGI proxy, comports himself with similar grace—dancing through a scrum of orcs, decapitating as he goes, or leaping along a line of masonry blocks as they tumble into the abyss. What this shift from "courtship" to "battle" as the idiom for dance signifies, in a larger sense, I leave as an exercise for the reader to work out. One thing it does mean is that moments that are in any way internalized—say, Thorin overcoming his own dragon sickness—get played out according to the logic of dance routines (in this case, Thorin leaping around a solid gold dancefloor that in turns writhes and swirls). It also means that the battle sequences are about as menacing as the finger-clicking gang encounters in West Side Story.

So: none of the character motivations make any sense, with the possible exception of Bilbo—and he gets much too little screen time in this, especially considering that the movie's main title refers to him alone. Not that the film's subtitle accurately reflects the movie either. I don't just mean the numeration; I mean the "battle" part. Some long shots of CGI hordes flowing over CGI landscapes aside, this movie has no interest in "battles" as such. It is interested in single combats, for which war, howsoever meager the causus belli, provides the opportunity. This individuation of war is part and parcel of the "defining" nature of these films taken together. They cannot, it turns out, think the collective at all; they can only think the individual—the fan favorite, the key prop, the singular. That's a pity.

It's a pity for the logic of a film called "The Battle of the Five Armies," but it's a bigger pity in terms of the adaptation from Tolkien. Indeed, I wonder if this—rather than the spurious addition of sexy elvish maidens, giant rock chewing worms, and Super Mario-ish combat sequences—is the main mismatch between Tolkien's source text and Jackson's films. Jackson thinks in Romantic and post-Romantic terms, of tragic-heroic heroes and heroines; his vision is fundamentally Byronic and Gothic. Tolkien, though, is a deeply pre-Romantic writer, who thinks in terms of communities, peoples, languages and the idioms of human congregation. These are his great themes, and his evils are things (like the Ring) that cut the individual off from human community.

It has something to do with the movie’s "main theme," I think. I daresay it's symptomatic of 21st-century attitudes to mistrust and despise politicians. Here the only good leaders are Bard (who, the film is quite clear, does what he does "for his family" rather than through any larger sense of social duty) and, I guess, Gandalf—though the wizard starts the film caged, beaten and too weak to stand, and never really garners any authority. Otherwise the Master of Laketown is venal and hypocritical, Thorin's shift from corrupted paranoid to noble warrior is positively manic-depressive and rewarded only by death, and Thranduil's haughty camp is as unreliable as it is unreadable (although he at least survives the end of the film). It may over stretch interpretation to read all this as a more meta transferred suspicion of creative authority—the author, Tolkien himself, who both justifies the entire undertaking and yet whose source material is so difficult to squeeze into the lineaments of modern Hollywood blockbuster form. Jackson and his team work through their confused mixture of admiration and resentment by bending and twisting that unreliable "authority" in riotous ways. The result is not, I'm sorry to say, very good.

Adam Roberts is a writer and critic of SF. He lives a little way west of London.