After years of economic depression, when Adolph Hitler came to power in the 1930s he re-armed Germany's army, navy and air force. Even before war broke out, French and Polish intelligence requested British assistance in restricting German imports of oil from Romanian oilfields. They wanted help to sabotage the barge 'tankers' carrying oil up the River Danube to Austria and then down the River Rhine to Germany's industrial heartland. Reducing oil reaching German refineries would mean less fuel for their warplanes, their submarines, warships, tanks, trucks and military transport. The British Ministry of Economic Warfare devised plans for Section D, the sabotage organisation of the Secret Intelligence Service (SIS), to blow up the cliffs of the Iron Gates gorge and block the Danube by sinking barges carrying cement and scrap iron. They transferred French and British barges to Turkey and devised plans to pay tug boat pilots not to work for the Germans. Bernard O'Connor's 'Blowing up the Danube' is a documentary history which includes declassified correspondence between the Foreign Office, SIS, the War Office, Section D, the Ministry of Economic Warfare, the Political Warfare Bureau, the Royal Navy and the Royal Air Force operating in the Mediterranean and, from July 1940, the Special Operations Executive, a top secret subversive organisation ordered by Winston Churchill to 'set Europe ablaze by sabotage.' It also uses contemporary newspaper reports and post-war historical research, biographies and autobiographies to provide a day-to-day account of the successes and failures of British intrigues in the Balkans during the Second World War.