During the Second World War, the British military and intelligence agencies had plans in case Germany invaded Spain and Portugal. This involved training British and Spanish agents to be secretly infiltrated to undertake sabotage operations on important lines of communication and liaising with pro-British locals. At the same time the Abwehr, Germany's military intelligence agency, paid young Spanish and Portuguese collaborators to undertake sabotage missions against Allied military and economic targets in Iberia but they had limited success. Italian saboteurs from the Decima Flotigglia MAS were more successful using underwater divers to attack Allied shipping. Using declassified files from Britain's National Archives, autobiographies, biographies and newspaper articles, this documentary history sheds new light on an unusual aspect of Iberian history telling a human story of international diplomacy, political intrigue, secret agents, clandestine warfare, military strategy, nationalism, and deception.