One afternoon towards the end of the 1980s a French academic working in a gloomy Parisian archive stumbled on a letter from Alexandre Dumas that led to an extraordinary discovery.

Dumas, the author of swashbuckling classics such as The Three Musketeers and The Count of Monte Cristo, wrote a final unfinished epic that had been lost for more than a century.

Years of painstaking literary detective work followed before the academic Claude Schopp was able to put the lost story back together again.

Next month it will be published in Britain for the first time, as The Last Cavalier, a stirring 750-page rampage through the Napoleonic wars, weaving together the classic Dumas themes of love, patriotism and vengeance.

The book has already been a hit in France, where it sold more than 250,000 copies.

Robin Harvie, the book’s editor at Fourth Estate, said that it would appeal to anyone with a thirst for adventure but also had an important literary significance.

“It’s a cracking read in the mould of the Three Musketeers and The Count of Monte Cristo. However, if you are a Dumas enthusiast it’s additionally interesting because it brings to a close his fictionalised account of this turbulent period of French history.”

The Last Cavalier is the third part of a trilogy about a band of aristocratic adventurers in the Revolutionary Terror and the Napoleonic Empire.

Hector de St Hermine, the central character, appears briefly in the previous two parts, Les Blancs et les Bleus and Les Compagnons de Jehu.

Dumas, the grandson of a slave, was an extraordinarily prolific writer who, in addition to his novels, also wrote plays, travel sketches, literary criticism, lectures, humorous essays and even recipes – anything that he could persuade newspapers to pay him for – to feed his prodigious appetite for women and high living.

Today he is the most widely read French writer, but it was only recently that he won recognition as a serious literary figure in his own country.

Throughout his lifetime and for much of the period since then his work has had to battle intellectual snobbery and barely concealed racism. He was buried in the Pantheon, the mausoleum for French national heroes, only in 2002.

In his introduction to the British edition, Mr Schopp recounts the complex tale of how he pieced together the text from untouched papers he found in the French national library.

In 1867, three years before he died, Dumas wrote to the director of the newspaper Le Moniteur Universel proposing “A novel of 4 or 6 volumes entitled Hector de Sainte-Hermine” which would follow the fortunes of a dashing young royalist and later Bonapartist soldier from the French Revolution to Waterloo, taking in the landmark campaigns of the era.

Schopp discovered that Dumas completed 118 chapters of the novel, which were serialised in the newspaper between January and October 1869.

“I must have been as happy as if I had discovered El Dorado. It was Alexandre Dumas’s final novel, a novel interrupted by illness and death, the novel on which his indefatigable pen finally had come to a stop.”

Mr Schopp’s work went far beyond following the paper trail. Dumas was a chaotic writer whose serialised work required extensive editing before it could be published in book form. He also left the story unfinished. Mr Schopp has supplied a final chapter and has written a sequel in line with Dumas’s vision which takes the hero across India and Russia to his eventual redemption. It will be published in France next month.

Literary swordsman

— Alexandre Dumas was born in 1802 near Paris, the grandson of a Haitian slave

— His father was the only mulatto general in Napoleon’s army but fell out with the future Emperor, leaving his family penniless

— The author married the actress Ida Ferrier in 1840 but soon separated after spending her dowry

— Dumas wrote more than 250 works, often with a team of assistant writers

— He is best known for The Three Musketeers and The Count of Monte Cristo, written 1844-45. The newly discovered novel is the only one set in the Napoleonic period

— The writer participated in the 1830 revolution in Paris and the 1860 Italian struggle for independence

— He died of a stroke near Dieppe in 1870

Source: Times database

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