BERNARD CORNWELL paces the ploughed battlefield at Agincourt and marvels that the French have not only left the scene of one of their greatest defeats pretty much as it was, but that they have built a little museum where visitors can pore over every detail of the unlikely English triumph.

“Very odd,” he mutters. If he had been French he would have “built a Carrefour supermarket on it”. Fortunately for tourists and bestselling authors of historical fiction, the locals didn't.

Cornwell could not resist writing about Agincourt in his 47th novel. “It's such a legend, isn't it? I was curious and the best way to find out what happened is to write about it. I rather believed what I learnt at school; that the good old English archers shot the French to bits.” The truth, he has concluded, was rather more complicated.

Azincourt (the French spell it thus) is told mostly from the perspective of Nicholas Hook, an English archer in Henry V's army. He encounters the grisly realities of war, finds love when he rescues a beautiful damsel in distress and bonds with the alpha male knights who swagger through these pages. Well, what else would you expect from the author of 21 testosterone-charged novels featuring the swashbuckling Napoleonic War hero Richard Sharpe, immortalised on the small screen by Sean Bean?

At Agincourt, little has changed in the past six centuries. The trees have retreated a bit so that the narrow area where Henry V and his archers vanquished the massed ranks of the French is a little larger than it was in 1415. But otherwise it is the same ploughed field that it was on the November day of battle. So enthusiastic is Cornwell as a guide that soon one is straining into the late afternoon sunlight for a glimpse of the English hammering their stakes into the soft earth. And at the other end of the field one half expects to hear the clank of arms from the massed French ranks.

Cornwell's book is drenched in blood and full of the misery of war. A long section deals with the unspeakable rape and butchery at the sacking of Soissons by the French. During and after the siege of Harfleur the English forces were ravaged by dysentery and by the time Henry's army, seeking to reach Calais, was confronted by the French at Harfleur it was sick, exhausted, hungry, demoralised and outnumbered.

There has been much debate about just how few were Shakespeare's “happy few”. A revisionist book by Professor Anne Curry said that the traditional figures of 30,000 French versus 6,000 English were more like 12,000 and 9,000. Cornwell sticks with the traditional view. “Something about Agincourt struck the imagination of Europe. If it was not the disparity of the numbers I don't know what it was.”

The night before the battle there was a downpour that followed days of rain, turning the battlefield into a quagmire. One advantage that the English may have had was that they were out of booze and so had no hangovers. The French, Cornwell concluded, probably did. “You can't go into these battles unless you are pissed.”

The French were frightened by the English longbowmen. No wonder. If the 5,000 archers averaged 12 arrows a minute, 1,000 arrows a second would have been hailing down on them. The French did not have longbowmen, they had slow-to-load crossbows and positioned them behind the men-at-arms where they could not see the enemy at key times.

Nevertheless, although the English arrows caused damage and some panic, they were not the full story. “We made a legend out of the arrows. If the arrows were so good how the hell did the French manage to reach the English line at all?”

A crucial factor in the battle is easy to understand as Cornwell leads us into the field and we immediately find it heavy going, even on a dry day. “It was not the arrows, it was the mud. It was awful. The archers had an effect, but not as huge as people think.” In their heavy armour the French struggled to wade through the mire. The press of French numbers on the narrow field made it difficult for them to wield their weapons when they reached the English and with their visors down against the arrows it was hard to see or breathe.

Cornwell gets excited as he explains what the encumbered French were facing. “Think of a pack of rugby forwards in armour. Would you want to face Martin Johnson in battle or Jason Leonard? They've just got out of the dressing room and they are going to win and it's ‘the fucking Frogs' and they are carrying poleaxes. You don't want to face those guys. I want to be behind him: ‘Go on Martin, kill him!'Martin Johnson with a poleaxe is a horrible thought. I'm so glad he's on my side.”

The French front line went down quickly and those following had to negotiate the bodies piling up in front of them. When the archers ran out of arrows they weighed in with pole-axes. “These guys are unbelievably fucking strong.” Cornwell's spoken language is almost as robust as his prose, where “putrid turd-sucking bastard” is one of the milder medieval insults.

Although there is no evidence that Agincourt is the origin of the two-fingered insult, it may have originated after the battle when English archers waved two fingers at the vanquished French to show that their firing fingers were still intact. A contemporary source had it that the French had pledged to cut off the fingers of archers, and that's good enough for Cornwell.

A war baby, born to a Canadian airman and a British woman, Cornwell was adopted and raised by members of the Peculiar People - joining an eminent line of authors, from Edmund Gosse to Jeanette Winterson, who were brought up in religious sects. He was liberated by university and worked for the BBC before marriage to an American took him to the US, where he started writing historical fiction. He has been there for 30 years and is a US citizen.

While he has written about the American Civil War his books sell best in Britain and at 64 he shows no sign of tiring of English history. In a way Azincourt's overriding theme is that of many of his other books. He once said that the Sharpe series could be summed up easily as: “Richard Sharpe kills Frogs.” “I probably did [say that]. I want to know how many whiskies I had had.” While writing the book he started to feel sorry for the French and came to respect the bravery of the men who charged the English line.

The long relationship between the two neighbours intrigues him. “The English define themselves in many ways against the French. Maybe France was the anvil against which the English sense of nationality was beaten out.” Pause. “Sounds a bit fucking pompous.”

Azincourt by Bernard Cornwall
HarperCollins, £18.99 Buy the book

The Times Cheltenham Literature Festival: Bernard Cornwell discusses the battle of Agincourt and his new book: October 19, noon
cheltenhamfestivals.com

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