[1] The character first appeared in the novel The Forbidden Territory (1933), along with his friends Simon Aron, Richard Eaton and Rex Van Ryn, whom Wheatley dubbed ‘the modern musketeers’.

The novels revolving around de Richleau's exploits ranged from occult stories, such as The Devil Rides Out, Strange Conflict and Gateway to Hell, to more straightforward thrillers based around non-supernatural intrigue.

His nose was aquiline, his eyes grey, flecked with tiny spots of yellow; at times they could flash with piercing brilliance, and above them a pair of ‘devil’s eyebrows’ tapered up towards his temples.

[9] In Codeword – Golden Fleece (1946) the Duke and his friends attempted to cripple the German war effort by business intrigues involving oil barges in neutral states among the Danube.

[10] After World War II, the Duke and his friends travelled to South America to foil another satanic cult, this time targeting Rex Van Ryn in the tale Gateway to Hell (1970).

His father loathed the French Republican regime and lived as a voluntary exile on an estate belonging to his wife in the Carpathian foothills near Jvanets on the Dniester River in what was then the Russian Empire.

[15] Until he reached middle age, Armand undertook soldiering as a living but diversified into commodity trading and high finance on his own account and in partnership with his friend the Jewish banker Simon Aron.

[16] His hobbies were big game hunting, fishing and cookery, and he enjoyed fine French wines and premium Hoyo de Monterrey Cuban cigars.

As a result of his studies into the occult, Armand became a believer in reincarnation and astrology and formed the view that the world was a battleground between the adepts of the Order of the Left-Hand Path and the Guardians of the Way of Light.

He was transported to French Guiana and was to be imprisoned on Devil’s Island, but managed to escape with the help of Channock Van Ryn, heir to the family-owned Chesapeake Banking and Trust Corporation of New York.

Disguised as a Russian teacher and nihilist called ‘Nikolai Chirikov’, de Richleau gained the trust of the anarchist Francisco Ferrer, the founder of the Escuela Moderna, set up to teach radical values.

There, Sir Pellinore persuaded him to renew his acquaintance with Colonel Dragutin Dimitriyevitch, the head of Serbian military intelligence and also the Grand Master of the Black Hand.

Using his Russian ancestry to full advantage, de Richleau was able to gain Dimitriyevitch’s trust and was initiated into the Black Hand, thereby learning of the plot to assassinate Archduke Franz Ferdinand of Austria in Sarajevo.

The resulting furor led the Austrian Empire to declare war on Serbia, and thus The Second Seal of the Book of Revelation was broken to let the demon of warfare loose upon the world.

As a Frenchman with British citizenship, he again came under suspicion and was only able to escape execution under martial law by murdering a German officer, Major Tauber, and an Austrian Baron, Colonel Lanzelin Ungash-Wallersee on their way to Berlin.

Managing to escape from the OGPU secret police in a gunfight the friends met an aristocratic French-born school teacher Marie-Lou (born 1911), since childhood a member of the household of Prince Shulimoff.

Richard and Marie-Lou were married in Vienna and settled in England at the Eaton family residence of Cardinal’s Folly, a mansion near Kidderminster, where their daughter Fleur was born on 5 September 1933.

[33] The duke was instrumental in the unexplained death of the French former priest and black magician Damien Mocata, whose Satanic cult planned to initiate Simon Aron on 30 April 1935, Walpurgisnacht, the night that The Devil Rides Out.

[36] During the political tension leading up to the Spanish Civil War, de Richleau was approached by his natural daughter Lucretia-José to recover a fortune in gold from the Madrid vault of her adopted father’s bank, the Banco Coralles, to prevent the ten tons of bullion from falling into the hands of the Loyalists, who would have sent it off to Soviet Russia to buy arms.

The duke, who had disguised himself as a French socialist ‘Hypolite Dubois’, and Richard Eaton removed over 800 gold bars surreptitiously from the bank and had these melted down and reformed as pots and pans.

As war threatened to engulf Europe once more, the duke (by now an implacable enemy of the Nazis) reformed the group to undertake a mission Codeword – Golden Fleece in Poland and Romania.

[38] Trapped between the advancing German and Soviet armies, De Richleau and his friends escaped to Romania, where they sought to cut supplies of oil transported by barge up the Danube to Germany.

[42][43] When Rex went missing from Buenos Aires after stealing a million dollars from the family bank of which he was a director in December 1952, the duke, Richard and Simon headed for South America, a journey that was to lead them to a veritable Gateway to Hell deep in the Amazon jungle.

While heading up the Latin American division of the Chesapeake Banking and Trust Corporation in Buenos Aires, Rex had begun a relationship with the film actress Silvia Seingiest (c. 1905–1953) and had been drawn into a Black Power group, controlled by the continent’s top Satanist, Don Salvador Marino, known as "the Prince".

With the duke’s help they were cleared of the charge and in February 1953 the three friends made their way to the Black Power training camp in the Salar de Uyuni, the salt flats of the Andean plateau in Bolivia.

Reunited, and with Silvia’s help, the friends defeated the Prince and his lieutenants: former SS Gruppenführer Baron von Thumm; Lincoln B Glasshill, a black American lawyer; the Moroccan El Aziz; the Jamaican Harry Benito; an Indian Satanist by the name of Kaputa; an indigenous Andean called Pucara; and their Zombie guards.

At a ruined Atlantean temple some 100 miles north of the Madeira River in the Amazon basin, Silvia interrupted a black magic ceremony, setting off a violent electrical storm in which she, the Prince and his acolytes perished.

The duke became embroiled in a fraud to remove a cache of diamonds without an export licence and assisted in the jailbreak of his legal advisor Douglas Rajapakse, who was also Fleur’s husband and who had been framed by a corrupt policeman.

The mighty Rex as Porthos, level-headed Richard as D’Artagnan and yourself as the subtle-minded Aramis; pitting our wits and weapons against every variety of rogue half-way across the world – from Russia to Haiti and Poland to Spain.

A film adaptation of The Forbidden Territory previously had been made in 1934, but replaced de Richleau with a character named Sir Charles Farringdon, played by Ronald Squire.