Updated edition of the ground-breaking 2017 publication that offered the first comprehensive account of the work of Section D of the Secret Intelligence Service.When Neville Chamberlain made his famous ‘Peace in Our Time’ statement in 1938, he may not have been aware that a new section of the Secret Intelligence Service, Section D, was already making plans to mount a political and sabotage war against Nazi Germany. This new form of warfare encompassed bribery, black propaganda and sabotage by agents described as having no morals or scruples. It disregarded the conventions of neutrality and was prepared to hit the Nazi state wherever it could do most damage.A scientific section was established to develop new types of weapons, and membership was extended beyond the traditional public-school ‘old boy network’ of British intelligence to work with German and Austrian resistance groups – socialists, trade unionists, Catholics and Jews. Section D’s plans ranged from leaflet campaigns in Germany, the sabotage of railways, factories and ports through to plans to block the River Danube by blowing up a mountain and an attempt to introduce foot and mouth disease into German cattle herds. Some aspects of the story are reminiscent of a Childers or Buchan novel – but they are true!The work of Section D prepared the way for the creation of resistance organizations in occupied Western Europe and was the forerunner of the Special Operations Executive (SOE). It also paved the way for the Auxiliary Units guerrilla force in Britain. As such, Section D represents a key stage in the development of irregular warfare.