On the morning of 7 April 1926 Benito Mussolini emerged into the Piazza del Campidoglio in Rome, having just opened an international congress of surgeons. He strutted towards his black Lancia idling in the square, chin tilted upwards in his usual comically pompous pose, taking the Fascist salute from a man in buckled shoes and quiver hat, as the waiting crowds chanted: "Viva Il Duce!" A group of students to his right began singing the Fascist anthem and as he turned his head towards them there was the sudden rasp of a gunshot.
Blood began to flow from Mussolini's nose. He looked up to see a small, elderly lady opposite him pulling the trigger of her revolver again - yet there was no second shot. When he realised that the pistol had jammed, Mussolini ordered the stunned crowd to stay calm; he dismissed what had happened as "a mere trifle" and then went back inside to clean up the flesh wound on his nose.
The story of Violet Gibson, the woman who tried to assassinate Mussolini, seems unpromising territory, beyond its moment of drama, for a writer. Il Duce survived with nothing worse than a ridiculous bandage on his nose and with most of his Fascist career ahead of him. She was touched by madness and her motives, despite conspiracy theories of the time, were opaque. This much she shared with Lee Harvey Oswald. But Gibson was no Oswald; she was a footnote to history, not someone who changed it.
In this new book, however, Frances Stonor Saunders has recovered the life of a woman who lived "at an impossible angle to the proper order of things". Stonor Saunders tells a story that stays long in the memory not only for its moments of wit and insight, but for the way it juxtaposes the madness of a demagogue with a woman drowning in her own unhappiness. She gives her subject more care and attention than anybody ever did in her lifetime.
Gibson was born in 1876, nine years before her father, Edward Gibson, the 1st Baron Ashbourne, became lord chancellor of Ireland. In a family for which "genealogy was a second language", she endured a stultifying childhood and was largely ignored by her parents. Like her brother Willie she flirted with Irish nationalism, but turned to theosophy and then, wholeheartedly, to Catholicism to satisfy her longing for emotional and philosophical consolation. At the age of 21 she went to Switzerland, the first step in a peripatetic life. In a village by Lake Geneva where she indulged in a fashionable rest cure, a young Italian was sleeping rough, bumming casual work. His name: Benito Mussolini.
The crossed paths of the exhibitionist Mussolini, hysteric of the balconies, eyes "projecting out like dangerous gooseberries" to adoring crowds, and the reclusive Gibson, who was never more at home than when sheltered in a convent, is what interests Stonor Saunders. The book follows their parallel lives - Mussolini's adoption of fascism and his rise to power; Gibson, troubled and ill, a fragile vessel waiting to be moved by some great spiritual quest. She set off for Rome, initially planning to kill the pope, whom she believed had betrayed Catholicism, but then settled on Mussolini.
Stonor Saunders shows how British leaders (and the Irish) flattered the Italian leader. A year after Gibson had burst the skin on Mussolini's nose with her ill-timed shot, Winston Churchill hailed his "triumphal struggle against the bestial appetites and passions of Leninism", describing him as "the greatest living legislator". The fear that Gibson's act might disrupt good relations with Italy was the greatest worry for the British diplomats who tried to resolve the case by having her declared insane.
In Stonor Saunders's narrative, Gibson is released from Italy, but to fleeting freedom only: she is taken by her sister to be incarcerated in an asylum in Northampton for the rest of her life. We feel the tension between her sense of having been saved and her unfolding awareness that she is to be condemned anew. In July 1943 Mussolini is overthrown and destroyed; two years later he is executed. Violet passes her remaining years forgotten and neglected, writing letters that are never posted, and dies in Northampton in 1956.
The Woman Who Shot Mussolini
Frances Stonor Saunders
Faber & Faber, 384pp, £20
Maurice Walsh's most recent book is "The News From Ireland: Foreign Correspondents and the Irish Revolution" (I B Tauris, £20)