Which novel is based on rumors of an actual attempt to assassinate French President Charles de Gaulle?

Frederick Forsyth's first and most admired novel, "The Day of the Jackal" (1971; film 1973 and 1997), is based on rumors he had heard of an actual attempt to assassinate French Pres. Charles de Gaulle. It is a thriller novel about a professional assassin who is contracted by the OAS, a French dissident paramilitary organisation, to kill Charles de Gaulle, the President, The OAS, as described in the novel, did exist and the book opens with an accurate depiction of the attempt to assassinate de Gaulle led by Jean-Marie Bastian-Thiry on 22 August, 1962.

The novel was published on 7June, 1971, in the year following the de Gaulle's death and became an instant bestseller. Set in 1963, it is about an Englishman hired by the Operations Chief of the OAS to assassinate General de Gaulle. He must be stopped at all costs. But how will the French Police and Commissaire Claude Lebel trace an anonymous assassin not on any bearucratic file? This question surrounds the novel.

In 1962, Frederick Forsyth, a correspondent for Reuters, hung out at the bars frequented by the underworld, the police and OAS sympathizers, staring at the wall and pretending to not understand French. Picking up the chatter about concentric rings of security around the President, he was convinced that only a complete outsider could even think of taking a shot. Later he created such a man and call him the Jackal.