Chemical weapons in the Rif War

During the Third Rif War in Spanish Morocco between 1921 and 1927, the Spanish Army of Africa dropped chemical warfare agents in an attempt to put down the Riffian Berber rebellion led by guerrilla leader Abd el-Krim.

These attacks in 1924 marked the second confirmed case of mustard gas being dropped from airplanes, a year before the signing of the for "the Prohibition of the Use in War of Asphyxiating, Poisonous or other Gases, and of Bacteriological Methods of Warfare". The gas used in these attacks was produced by the "Fábrica Nacional de Productos Químicos" (National factory of chemical products) at La Marañosa near Madrid; a plant founded with significant assistance from Hugo Stoltzenberg, a chemist associated with the German government's clandestine chemical warfare activities in the early 1920s who was later given Spanish citizenship.

The Spanish bombings were covered up but some observers of military aviation, like Pedro Tonda Bueno in his autobiography La vida y yo (Life and I), published in 1974, talked about dropping toxic gases from airplanes and the consequent poisoning of the Rif fields. Likewise, Spanish Army air arm pilot Ignacio Hidalgo de Cisneros, in his autobiographical work Cambio de rumbo (Course change), reveals how he witnessed several chemical attacks. Years later, in 1990, two German journalists and investigators, Rudibert Kunz and Rolf-Dieter Müller, in their work Giftgas gegen Abd El Krim: Deutschland, Spanien und der Gaskrieg in Spanisch-Marokko, 1922-1927 (Poison Gas against Abd El Krim: Germany, Spain and the Gas War in Spanish Morocco, 1922-1927), proved with scientific tests that chemical attacks had indeed occurred. The British historian Sebastian Balfour, of the London School of Economics, in his book Deadly Embrace, confirmed massive use of chemical arms after having studied numerous Spanish, French and British archives. According to his research, the strategy of the Spanish military was to choose highly populated zones as targets. Additional evidence is found in a telegram from a British official, H. Pughe Lloyd, sent to the British Minister of War.

...
Wikipedia