Your first choice is Political Murder: From Tyrannicide to Terrorism.

This is the most historically far-reaching of all the books I’ve chosen, and raises interesting questions about the causes of assassination and the different attitudes surrounding it during different time periods and in different cultures. Although the book is organised chronologically, beginning with Classical Antiquity, and looking at notions of vengeance and judgment in the Bible, it continuously raises comparisons across time and place, whilst avoiding what the author describes as ‘laboured’ historical analogies. The result is always challenging and thought-provoking.

Ford looks at three different concepts of politically motivated killing in this book – with the broadest being political murder (from the specifically targeted to random killings), assassination and then, specifically, tyrannicide. He explores the origins and definition of the word ‘assassination’ and how that has evolved. The word is thought to have its origins in the Ismaili Muslim sect, the Hashishin, operating in the Middle East from 1090 to 1272, a sect which operated with a great deal of secrecy, including murder of political opponents. The Crusaders then picked up on it and the Hashashin gained a reputation for ruthless, covert killing. Marco Polo elaborated on the myth, describing a potent and irresistible blend of drugs and sex, in which recruits were drugged and promised an afterlife full of young maidens in exchange for unquestioning fealty. The notion of the assassin as working covertly, often as a result of a plot or conspiracy, had pretty much taken root by the 14th century.

Equally important with the evolution of the idea of assassination are the debates about the justification for politically motivated killing, and any study of assassination will look at the different philosophical debates trying to justify tyrannicide. A significant treatise debating the rights and wrongs of tyrannicide, Policraticus, was written by John of Salisbury, Thomas Becket’s clerk. One would expect a theologian to argue against any kind of murder, but John of Salisbury was responding to a debate that had been going on since antiquity, arguing the rights and wrongs of murdering a tyrant. A tyrant was defined as such either by the manner or his rule, or the means by which he had gained his power (tyrannus in regimine or tyrannus in titula). For John of Salisbury and many of his peers, God was the highest authority: if the king was against the law of God, his assassination was justifiable.

Tell me about the assassination of Henri IV book.

Coincidentally, the 400th anniversary of this assassination has just passed – the event happened 14 May 1610 and the French are making a big deal of commemorating it. Henri was a fascinating king, uniting France by his conversion to Catholicism, ending a period of extreme religious turmoil and responsible for the Edict of Nantes, granting formerly unheard of rights to Huguenots until it was revoked by his grandson Louis XIV. He was, by all accounts, charming, witty, intelligent, and had a very colourful personal life, twice married, many mistresses, that kind of thing. He was also responsible for a lot of the city planning in Paris, including the beautiful Place des Vosges. Following his death a contemporary diarist described the city going into a ‘frenzy of mourning’ with much tearing of clothes and public wailing. I grew very fond of Henri IV while I was researching this book.

The great controversy about Henri was that he was originally a Huguenot at a time when there was great religious strife in France, so the idea of a Huguenot on the throne was unthinkable. His conversion to Catholicism was an attempt to unite the country, (his famous but probably apocryphal quip that ‘Paris is well worth a mass’ reveals the depth of his faith). There were up to 16 attempts on his life but, of course, only the last one was successful, by a religious fanatic who believed Henri to be a heretic who should not be on the throne – according to the classical definition, a tyrant by usurpation. The Huguenot minority were disappointed by his conversion, the Catholic majority suspicious of it, and Henri himself had such a tenuous claim to the throne – he was something bizarre like the 17th cousin of the previous king, if that’s possible ­– no wonder he had so many enemies.

Who killed him?

François Ravaillac. He was quite a pathetic character who had had a difficult and miserable life.

Aren’t they all?

Yes! Although he wasn’t the only one to question Henri’s right to sit on the throne. Ravaillac himself was very devout in the first place, but then his devotion became fanatical. He joined a very austere order, the Feuillants, but was asked to leave because he was too extreme – too into all his scourging and physical mortification. I mean, if you join an extreme sect and they ask you to go… He was not balanced. Later, he tried to join the Jesuits, and was turned down on the basis he had already been a member of the Feuillants. By this time he was having religious visions. Rather touchingly, one of the Jesuit brothers suggested what he really needed was a good night’s sleep and better food. It makes you wonder how many religious visions were really a result of malnutrition and physical deprivation.

How did he do it?

If it were a Victor Hugo novel you’d think it was a bit far-fetched. Henri IV was moving through Paris in a cumbersome carriage pulled by six horses and it got stuck at a crossroads near what is now the Place des Innocents, in the Les Halles area of Paris. Ironically, this crossroads was going to be Henri’s next project – widening it to improve traffic flow. Anyway, Ravaillac was able to approach the carriage and stab him. By this time he had been having visions telling him to kill the king, and he had tried to gain an audience with him on more than one occasion with that aim in mind. Henri was taken to the Louvre but pronounced dead on arrival. Obviously, Ravaillac was immediately apprehended and executed in the most horrible way. Interestingly, he was convicted of parricide and not tyrannicide, which says a lot about the position of the monarch in French society.

How was he executed?

Well, the hand that had stabbed Henri was cut off and the stump dipped in boiling lead. There was a contemporary belief that the limb that carried out the crime could somehow be possessed, and was punished separately. Then he was hanged until he was nearly dead, drawn and quartered very slowly… The sentence said that his soul must leave his body drop by drop. It was a ritualised killing and what he endured was specifically tailored to his deed. Amazingly, he remained conscious through most of the ordeal. It really is unthinkable.

Tell us about Murdering McKinley.

President McKinley was assassinated in 1901 by Leon Czolgosz, a self-confessed anarchist, who approached McKinley at the Pan-American Exposition in Buffalo, New York, with his hand wrapped in a handkerchief that concealed a gun. He was immediately apprehended and would have been beaten to death by the crowd had the police not intervened. As he was strapped into the electric chair he made a dramatic, 11th hour statement: ‘I killed the president because he was the enemy of the good people! I did it for the help of the good people, the working men of all countries!’