The two 'world wars' (ie., the european tribal wars which dragged the rest of the world into their mess) were the lessons from which the white supremacists/imperialists decided that they would never war with each other, but prefer to unite in collective war, despite tensions between them, against Black n Brown Humanity, here is brit prime minister harold macmillan on 03 feb 1962:
"what the two wars did was to destroy the prestige of the white people. For not only did the yellows and blacks watch them tear each other apart, committing the most frightful crimes and acts of barbarism against each other, but they actually saw them enlisting each their own yellows and blacks to fight other Europeans, other whites. It was bad enough for the white man to fight each other, but it was worse when they brought in their dependents."
(Quoted on p40 in a book I can't recommend enough! - 'The Silent War: imperialism and the changing perception of race', pluto press, 1998)