Set in England in 1215 during the Baron's War against King John, the film has a strong narrative line founded on the siege of the strategically-important Rochester castle in Kent. Is it historically accurate? Not especially. Is it for the most part engrossing and well done? You bet.
A party of proto-democratic, pro-Baronial rebels headed by Baron d'Albany (Brian Cox) and his "Seven Samurai" type band of hardnut common soldiers, gains some elite military leadership in the form of troubled Templar Thomas Marshal (James Purefoy). Seizing Rochester Castle before the King (Paul Giamatti) can occupy it, the bulk of the story tracks the grim cat-and-mouse game, interspersed by brutal hand to hand fighting, characteristic of medieval siege warfare.
The film delivers suitably gory and violent combat, mostly very effectively. It conveys a sense of visceral, desperate fighting, although in my opinion there is a limit to the dramatic impact of such scenes. It makes up for that by at least taking a moment to consider how exhausted and disgusted these fighting men are by what they do.
In the film's quieter moments, Marshal is depicted as a Templar with a conscience, who has returned from crusade spiritually scarred by the contradiction of being a soldier for God. His mentoring of d'Albany's young Squire Guy (Aneurin Barnard) and his temptation by Lady of the castle Isabel (Kate Mara) form the emotional heart of the story. As essential dramatic relief, these elements are mostly well-done, albeit not exactly original.
One thing the medieval genre can do well is raise the thematic question of fighting for a cause versus fighting for pay or survival. There is an idealism at its heart which can make a nice change from sometimes mundane and prosaic, kitchen sink contemporary drama. Ironclad takes a satisfying nod in this direction.
Purefoy is uniformly excellent, conveying the brooding quality of his character with a ton of conviction. It can be hard for actors to pull this off without caricature, but he inhabits the screen like an old-fashioned leading man, and you can only lament that there aren't enough British films or roles for this kind of actor.
It's also refreshing to see Charles Dance and Brian Cox playing "good guys" for a change, and the always compelling Paul Giamatti (doing a creditable English accent) has some stand out moments and a gloriously enraged barnstorming speech as a man born, but not fit, to be King.
All in all, this is good, well-crafted old-fashioned story-telling. Some reviewers have criticised it for being too generic (it's a genre movie) while some have called the film ambitious, as if that's a fault. Could it have been deeper, more authentic, more inventive? Perhaps. But it is head and shoulders above most of the tediously bubble-gum "action" films out there. I applaud it.
If you're a fan of historical movies, it's thoroughly enjoyable. It deserved better success than I think it got. Why not give it a try?