A battalion of helmeted, khaki-uniformed riflemen charges down a steep hill. One takes a dramatic tumble, clutching his hands to his chest. His pals keep going regardless: in the heat of an attack, there's no time to stop and help the wounded. Though these men are instantly recognisable as First World War infantry, there's a marked absence of blood, and the brilliant green of the hillside more resembles the grounds of a National Trust property than the muddy fields of Flanders.

In fact, it probably is - for this isn't the British Army, or even the set of a new BBC drama, but the parallel world of battle re-enactment, where bands of enthusiasts get together at weekends for a spot of harmless jousting and (blunt) sword-on-sword action. "Somebody put a sword in my hand and it felt like an extension of my arm, and from then on I was addicted", says a knight right out of the Middle Ages. "I'm an extrovert, I'm a show off, I can be whatever I want to be", says another. Since the 1960s, 'living history' has changed from propaganda to pleasure, and it's become a booming industry from which increasing numbers of people make their living.

But what is it about the past that inspires such devotion from these living historians? And what drives them to spend thousands of pounds on weapons, armour, authentic costumes and even tanks? Why do the public flock to these displays and what controversies have these re-enactors provoked in the public and with academics? With unique access, Charging Into History captures the biggest re-enaction events in Britain and takes an in-depth look at this phenomenon's growth and popularity. It provides a glimpse into an industry that comes across as ordinary as it is bizarre. Re-enacting history settles old scores, but brings with it a whole new moral minefield.