It marked a turning point in the English Civil War, but now a new study has overturned accepted wisdom on the course of the Battle of Marsdon Moor. Nick Morrison reports

IT'S not much to look at: a vast expanse of wheat stretching almost to the horizon. A dirt track winds its way through the field, and by the side of the Long Marston to Tockwith road which borders it to the north, stands a stone obelisk. This is the only clue to the pivotal role this otherwise nondescript plot of land played in our history.

For this field, a few miles west of York, was the site of the Battle of Marston Moor, one of the most important military engagements ever fought on our shores. It was a battle which was to prove a key moment not just in the English Civil War, but also in the development of our democracy.

It was Marston Moor which saw Royalist invincibility, under the dashing Prince Rupert, exposed as a myth. It was Marston Moor which saw the North irrevocably lost to Charles II in his struggle to hold on to his kingdom. And it was Marston Moor which gave Oliver Cromwell the reputation which was to lead to his eventual installation as Lord Protector, the first head of our first, and so far only, republic.

Marston Moor was the biggest and bloodiest battle of the Civil War, and, with more than 40,000 men in five armies involved, it was probably the biggest engagement ever fought on English soil. It was also a slaughter: around 4,150 Royalist troops lost their lives, compared with around 300 on the Parliamentarian side under the command of Sir Thomas Fairfax.

But the actual course of this most crucial of battles has been the subject of much debate among historians. It may have been well known that the Royalists were taken by surprise on that evening of July 2, 1644, but why was the battle quite so one-sided? What exactly happened to the white-coated infantry of William Cavendish, Earl of Newcastle, whose last stand has been compared with that of Custer's 7th Cavalry? And where was the famed Rupert while his army was being massacred?

Finally, almost 359 years after the event, these questions can be answered definitively, in the process overturning much of the accepted wisdom. Thanks to the most comprehensive study of a battlefield anywhere in the world, we now know as much about the Battle of Marston Moor as we probably ever will.

And much of that is due to Paul Roberts, who has spent the last 18 years studying the battlefield. His technique has been to survey virtually every inch of the ten kilometre square field of conflict, on the basis that the siting of artefacts will provide an incontrovertible picture of what happened that day. Contemporary accounts may be influenced by the author's bias, but no one can argue with the lead shot and horseshoes of war.

During those 18 years, Paul, working with around 30 volunteers armed with metal detectors, has spent around 340,000 hours at Marston Moor, walking the equivalent distance from York to South Africa, and back, and on one occasion sleeping in the field at temperatures of minus 7C. But in the process he has amassed the largest collection of Civil War artefacts in existence: bullets, cannon balls, horseshoes, pike tips and horse brasses. Musket shot alone counts for about 14 hundredweight of the find.

The location of each find was meticulously marked on a map, with different colours to denote the type of artefact, allowing the picture to unfold before Paul's eyes. And this led to some rather surprising conclusions, documented in a book co-written with historian Paul Newman, who died before it could be published.

"There were five armies at Marston Moor, with about 15,000 muskets. Each man has got 12 shots, and firing one a minute, after 12 minutes, you would have 180,000 musket shots," says Paul. "But we found the shots were predominantly going into the Royalist side, and the conclusion is they weren't ready."

Although it was generally accepted that the Royalists were taken by surprise, Paul's findings show this was to a much greater extent than had previously been thought. The Royalist front line troops were in a ditch, and had been stood down, meaning their weapons had been unloaded. By standing in that ditch himself, Paul estimated that they would only have seen the advancing Parliamentary infantry when it was some 60-70 yards away, giving them barely enough time to fire a single volley, accounting for both the lack of bullets on the Parliament side, and the disparity in casualties. The battle was virtually over before it began.

Paul's study also revealed the location of Prince Rupert, nephew of the king and the hitherto undefeated general who carried the Royalist hopes of victory. Thinking there would be no battle that night, Rupert was settling down to dinner when the Parliamentary assault began, and barely had time to don his armour and mount his horse before he saw his army fleeing past him, routed by the then-unknown Oliver Cromwell.

The discovery of one of the Prince's personal effects, at the spot known as Four Lanes Meet, has pinpointed the exact spot where Rupert sat down to supper that night.

But perhaps the most startling revelation of Paul's research concerns the fate of Newcastle's famed white-coated infantry, who had garrisoned York before taking the field against the king's enemies. The location of their last stand has been a matter of dispute among historians, but Paul believes he has come up with the last word on the subject.

One theory was to position this phase of the battle at a place called the Atterwith enclosures, the rival position was that it was at White Syke Close. But the spread of the artefacts led Paul to dismiss both these views; instead he has placed it in the centre of the battlefield, on the Marston to Tockwith road, just south of the ditch.

"These findings have radically altered our view of what happened at Marston Moor," says Paul. "It is the most comprehensive study of a single battlefield, not just in the English Civil War, but any war in history. This shows, for the first time in 359 years, the Battle of Marston Moor in colour.

"Historians had read the accounts of the battle, but until now they didn't have the evidence on the ground. What we have done is like Through the Keyhole: the clues are there. This artefact evidence from the ground has brought everything into play, and it is virtually impossible to argue with it."

But, as well as enabling him to rewrite history, spending 18 years researching the battlefield has had a more personal impact.

"Marston Moor has become very special to me: I have formed a love/hate relationship with it. I have slept on the positions at minus 7C and nearly died; I have lived the experience," Paul says. "I have had some very, very good experiences there, and some very bad ones, but it has been worth it."

* Marston Moor: The Battle of the Five Armies by PR Newman and PR Roberts (Blackthorn Press £19.95). A CD Rom of the battlefield survey is also available from Blackthorn Press