Italy invaded Ethiopia from Eritrea and Somaliland on 3 October 1935 without declaration of war. Italian forces used mustard gas sprayed from aircraft against Ethiopian troops, civilians, livestock and water sources, in violation of the 1925 Geneva Protocol to which Italy was a party, and bombed field hospitals marked with the Red Cross. Addis Ababa fell in May 1936 and the country was annexed to Italian East Africa. The League of Nations condemned the invasion and imposed limited economic sanctions that excluded oil and were abandoned in 1936, an episode widely seen as demonstrating the League's ineffectiveness. Resistance continued, and after an attempt on the life of the viceroy Rodolfo Graziani on 19 February 1937, Italian soldiers, Blackshirts and civilians killed Ethiopians in Addis Ababa over three days in the massacre known as Yekatit 12; Ian Campbell's reconstruction from Italian, Ethiopian and diplomatic sources puts the dead at roughly 19,000 to 20,000, against Ethiopian claims of 30,000 and much lower Italian figures. Reprisals extended to the massacre of the monastic community of Debre Libanos in May 1937. No Italian was ever tried: Ethiopia's request for extradition of Italian officers after the war was not granted by the Allies.
Fascist Italy invaded and annexed Ethiopia, used chemical weapons against its forces and population, and massacred civilians in Addis Ababa in reprisal
Ethiopia had no census before 1984; McEvedy and Jones and Italian colonial estimates put the population at roughly 10-12 million in the 1930s. Estimates of Ethiopian deaths from the war and occupation range from about 350,000 to the Ethiopian government's post-war claim of 760,000; the Yekatit 12 reprisal in Addis Ababa in February 1937 killed between 3,000 and 30,000 people over three days depending on the source, and was followed by the massacre at Debre Libanos.
Ethiopian deaths across the invasion and occupation of 1935-41 are estimated between about 150,000 and 760,000; the Ethiopian government's postwar claim to the reparations commission was 760,000, while more conservative estimates count roughly 275,000 combatant and civilian deaths in the war of 1935-36 plus tens of thousands in the reprisals of 1937 and the guerrilla war. The Addis Ababa massacre of February 1937 accounts for an estimated 19,000 to 30,000 of the total, depending on the source. Italian deaths were far lower. All figures rest on estimates rather than registration.
The use of mustard gas against troops and civilians, the killing of civilians in Addis Ababa in February 1937, the massacre of the clergy of Debre Libanos and the destruction of churches and villages are documented in Italian military orders and colonial records, in contemporary diplomatic and Red Cross reporting, and in Ian Campbell's archival reconstruction.
Ethiopia, United Kingdom