King Robert I of Scotland, commonly known as Robert the Bruce, was born in 1274 and died in 1329; he was crowned in 1306 and held the crown until his death. Andrew Mackenzie’s film about him covers only a few of those years, however, beginning in 1304, with the renewed submission of his family to King Edward I of England and the king’s casual use of his largest siege engine—a gigantic catapult—against Stirling Castle, and ends in 1307, after Bruce had resumed the fight for independence but suffered several major defeats, with his stunning victory over the English at Loudon Hill and the death of King Edward. The English effort to subdue Scotland continued into the reign of Edward II and intermittently for centuries afterward, bur Robert—who had fought sporadically in the anti-English campaigns of William Wallace, though not always, as Mel Gibson’s “Braveheart” showed, on the side of that nationalist leader—reversed the tide in 1307, and so the script by Mackenzie, Bash Dorian and James MacInnes closes with the beginning of his real march to royal glory.

The picture holds to the general chronology, though it fiddles with the facts for dramatic effect. It conflates the final siege of Stirling with Robert’s marriage to Elizabeth de Burgh, daughter of Edward’s lieutenant the Earl of Ulster, for example (which actually occurred earlier), and portrays the union as purely an arranged match though it actually seems that they were romantically involved earlier on; the screenplay ignores that so as to depict Elizabeth as initially disdainful of Robert and have her warm to him over time. And while it doesn’t ignore the animosity of Edward I against Robert when he claims the throne after the execution of Wallace and raises the flag of rebellion anew, the writers choose to cast their narrative primarily as a conflict between the Scotsman and Edward of Carnarvon, the future Edward II. So they suggest they were childhood friends and rivals who’d had a falling out, bookending the film with swordfights between them; it also situates Edward I’s death before Loudon Hill, though it actually occurred months later.

One doesn’t expect precision in a film based on history, though, and you can chalk up such fudging to dramatic license. Though casting the story primarily in terms of a face-off between Bruce and the English prince places the younger Edward personally in the center of events —like the capture of Robert’s brother Nigel in 1306 or Loudon Hill itself—where he was not actually involved, you can understand why the script’s trajectory demanded such alterations to the record. This is not a documentary, after all, though it is honest enough to depict Bruce’s killing of his chief Scottish rival John Comyn in 1306 for what it was—a cowardly murder, pure and simple, though perhaps a necessary one.

The question is whether “Outlaw King” works as drama, and the answer is, unfortunately, only sporadically. Mackenzie aims for an epic feel, and despite some impressive locations the film comes off as several sizes too small for its ambitions. Perhaps it had greater scope in the longer, two-and-a-half hour version that premiered at the Toronto Film Festival some months ago (the editing is credited to Jake Roberts); one suspects that certain sections might have at least been more coherent (the so-called Feast of the Swans at which Prince Edward was knighted is here little more than a lurid jumble, for instance).

But one suspects that mere expansion wouldn’t fix the problem, because a good deal of the film is lethargically paced, even dull. True, the Loudon Hill sequence is as raucous and bloody as any aficionado of medieval whack-‘em violence could wish, and an earlier recreation of the disaster at Methven, where the naively chivalric Bruce allowed his force to be attacked unawares and nearly wiped out, is impressively done. But a good deal of the picture shows Bruce and his haggard host trudging along mountain paths after Methven, and it is not enlivened by a rather sloppily staged episode depicting their escape to Rathlin Island while under assault from the hostile MacDougall clan. A subplot about Bruce entrusting his crown to a young page, who safeguards it until Loudon Hill, is, moreover, corny—you might wonder whether it was inspired by the saccharine close of the musical “Camelot.”

Chris Pine’s bland performance as Bruce is no help, either. He and Mackenzie worked well together in “Hell or High Water,” but here the actor seems miscast, and seems to know it, shedding a solemn, wooden air only very occasionally to rouse himself to an emotional outburst. Florence Pugh brings greater spark to Elizabeth (her scenes in captivity are forcefully done), and Stephen Dillane a growly authority to Edward I, though he can’t efface memory of Patrick McGoohan’s supremely eccentric turn as the wily monarch in “Braveheart.”

Luckily for those who might be in danger of dozing off in the welter of verbal sparring and thick brogues in the film, there are a couple of performances that lift the energy level. One might quarrel with the prominence given to Prince Edward in the script, but Billy Howle plays him with full-throated nastiness. Even more vigorous is Aaron Taylor-Johnson, fitted out with a sharp-edged beard, who’s positively ferocious as James “Black” Douglas, Robert’s most fanatical follower. It’s a pity the narrative doesn’t go to 1329, when we could see him carrying Bruce’s heart, in a silver casket, to the Holy Land, only to be cut down in Spain fighting the Moors there.

On the other hand, that would have made for an inordinately protracted movie, and what we have now, even after its reduction by a half-hour, is already quite long enough. You have to credit Netflix for producing a film on so grand a scale—the work of production designer Donald Graham Burt, costumer Jane Petrie and cinematographer Barry Ackroyd is good enough that one regrets that most viewers will see it on smaller screens, when it really deserves a full-sized auditorium. But though “Outlaw King” may well appeal to the nationalist sentiments of many Scots, for most others it will be a rather plodding history lesson—one with some factual adjustments for dramatic purposes.