This forensic study of recently opened documents in Britain's National Archives reveals for the first time the details of an officially unnamed secret operation authorised by Winston Churchill in 1940 to keep Spain neutral in the Second World War through the financial manipulation of Spanish generals.

Viñas focuses on the crucial roles played by the British ambassador in Madrid, Sir Samuel Hoare; the embassy's naval attaché, Captain Alan Hillgarth and – hitherto unknown to Anglophone readers – the Spanish businessman, Juan March, perhaps one of the richest men in Spain at the time and a financial backer of the military conspirators sparking the Spanish Civil War in 1936. He identifies the likely recipients of the bribes, how they were paid and the influence they wielded on Spain's dictator, General Francisco Franco, who together with his notorious foreign minister, Ramón Serrano Suñer, was minded to enter the war on the side of the Axis. With masterly analysis, this book places the bribes paid by Britain in the jigsaw puzzle of why, after all, Spain remained neutral.

This volume is a pioneering and important contribution for scholars and students of Anglo-Spanish relations, Spanish-Axis relations and wider strategic aspects of the Second World War.