In 1765, the king of Burma sent his armies into what's now called Thailand, to take down the 400-year-old kingdom of Ayutthaya. Surprisingly though his fiercest opposition apparently didn't come from the capital city, but from a village called Bang Rajan. This is its story.

Bang Rajan is a big deal in Thailand. So far they've made two films about it, the other one being in 1966, not counting the 2010 sequel Bang Rajan 2. This one had a budget of 50 million baht, about four times the cost of a normal Thai movie, and was a domestic box office smash. Internationally it took a while for the word to get around, but it won the second prize for Best Asian Film in Montreal in 2003 and then the following year got a limited release in US cinemas, presented by Oliver Stone.

Unfortunately it came slightly too early for the Thai export wave, triggered by the worldwide runaway success of Tony Jaa's muay Thai martial arts in Ong Bak. It still built a bit of a following, though.

It's worth knowing what you're going to see. It's violent, especially the last half-hour, but it's also long and slow. It's not one of Thailand's many action films, you see, but instead belongs to a different Thai movie tradition: the historical epic.

It begins with a battle scene set during the night. This is realistic, but confusing. You don't normally see action scenes set in near-complete darkness and this demonstrates why. If you're lucky, you'll see silhouettes. Nevertheless it's clear that there's a lot of killing going on, with our Bang Rajan heroes using guerilla tactics to ambush and tear apart the far bigger and better-organised Burmese. This establishes the film's violent credentials and allows it to settle back into nearly an hour and a half's worth of regular movie. Thai villagers fight, recruit a new leader and get teased by their women. There's a marriage proposal and a woman who learns that she's pregnant. There's a monk. There's an invincible drunkard with two axes, who's the nearest you'll get to a comedy character. All this is slower, duller and more feminist than I'd expected, with the villagers basically getting on with their lives even as they fight a war to the death against the invaders.

They also despise Burma. It's almost a second religion for them, although this becomes more reasonable later on after we've had a look at women's severed heads and a macabre pseudo-Christmas tree. "We united in our hatred of the Burmese."

All this is... okay. That first hour and a half is passable and has the running time of a regular movie in itself, but it's not the most compelling I've ever seen. The film does pretty well at bringing these 18th century Thai peasants to life for us, but they're not particularly interesting characters. The drunkard made me laugh and Mr Mega-Moustache was visually amazing for the obvious reason, but that's about it.

No, I tell a lie. The women are good. This film gives far more attention to its female characters than you'd expect of a film set hundreds of years ago about peasant guerilla warfare against an invading army. There's also a would-be rapist who gets an arrow in the throat.

Most of the film I wasn't completely gripped by. It was pretty good at what it did, but it lacked the personal touch that you might find in other historical epics, e.g. apparently the same director's later Khunsuk. What it has instead is integrity and a feeling of authenticity. The violence is convincing and never for a moment did I fail to believe that I was looking at peasants in the Thai jungle hundreds of years ago. I admired it from a slight distance, if that makes sense. However the film kicked into gear for the final act, in which a really bad mistake is made and things get grim. The final battle in particular is the part you won't forget. This isn't the usual Inevitable Hero Battle. Again the violence feels realistic, which is impressive and scary when we're talking about a massive pitched battle and means that people are going to die like flies.

There are some powerful images in there. I'd particularly cite the married couple. You'll know when you see it. Oh, and the women fight too, despite their menfolk having previously been urging them to concentrate on being protective and nurturing. "Get back to the kitchen. I'm hungry." That adds still more power to the finale.

There are also other enjoyable details, simply as a result of being in Thailand in the 18th century. That buffalo is awesome, as are the Burmese generals' bonkers hats.

I need to see more Thai cinema. So far I've sampled their gay comedies (The Iron Ladies) and a 1960s retro noodle Western that's like nothing else that's been made for half a century (Tears of the Black Tiger), but there's a ton of stuff I haven't yet got into. Ong Bak, obviously. Horror, like Nang Nak or The Eye. Other historical epics. Uncle Boonmee Who Can Recall His Past Lives, which is actually in my queue. They're not up there with South Korea or Japan, but they still have a solid, diverse movie industry that's rightly drawn plenty of international attention.

The last half-hour is what makes this film special. Without that, it would have merely been good, albeit still operating on a budget and a scale that had never been attempted before in a Thai film and hence through its success helping to raise the ambition levels of their entire industry. It's a landmark movie. You don't get many of those. However more important for me as a viewer is that final battle, which is one of the more unforgettable I can remember. Only Takashi Miike's 13 Assassins comes close recently for me in that regard. Overall the film's a bit too slow and undercharacterised for me to recommend freely, since you'll need to show patience to reach the end. However it's also sincere, surprisingly subtle in some of its character work and has a powerful ending. You could do much worse.