Gary Thompson: Gary Thompson interviews 'Centurion' director Neil Marshall

AS A LAD in Northern England, Neil Marshall used to stand at the ruin of Hadrian's Wall and wonder about the forces that led to its construction.

"I'd look out on a misty rainy night and wonder what a Roman soldier might have thought, standing in the same place centuries earlier. What were the Romans afraid of, what was out there? Why did they retreat behind this massive structure?"

Fast-forward a couple of decades, and Marshall, now a director of horror movies, is sitting in a pub, spitballing ideas for his next project when a buddy asks him if he's ever heard of the legend of the 9th Roman legion.

"An entire legion, three or four thousand men, marches into Scotland and into the mist and vanishes without a trace. I figured there had to be a movie in it," said Marshall, who helmed the cult horror fave "The Descent" about women who encounter bloodthirsty creatures in a rural cave.

"At first, given my background in horror, I was prone to go down a supernatural road. Maybe an alien spaceship, or the Loch Ness monster. But the real history turned out to be much more interesting."

It's likely, based on what historians now know, that the legion was badly beaten by barbarian Pict hordes in a guerrilla war the Romans didn't know how to fight. Such a defeat was a political disaster for Roman leaders, who squelched reports of the ignominious retreat, and quietly disbanded the 9th legion. Emperor Hadrian then built the wall, putting a 60-mile buffer between Rome and the enemy.

Marshall's action- and blood-drenched "Centurion" begins with the legion's massacre at the hands of Pict tribes. The rest of the movie is one long brutal chase, as barbarian riders pursue a handful of Romans (led by Michael Fassbender) who want nothing but to return home.

The movie is told mostly from the (sympathetic) point of view of Roman soldiers, whose enemies include their Pict pursuers and shiftless Roman politicians, who view the return of surviving witnesses to the legion's defeat as an inconvenience.

This soldier-friendly story of an occupying army fighting an unpopular war against entrenched guerrilla forces has led many to wonder whether Marshall isn't making some reference to current-day Afghanistan.

"To be honest, when I set down to write it, it had no context at all. It was as I was finishing that I considered the parallels - a superpower invading a country and encountering protracted guerrilla warfare and struggling with it for a long period of time. Of course for the Romans it was a REALLY long time, 60 or 70 years," Marshall said.

"I left it at that. If people want to make those connections, that's fine. That's good. I love that. My goal was to make an action-adventure movie, a piece of escapism, period. I'm not a political filmmaker. Still, it's interesting to consider that some of the same things happening today were also happening 2,000 years ago."