out of curiosity
what would it be
Well that's subjective. Could be the decimation of the Americans/Australians, the enslavement of the Africans and others, the systematic racism put into place in almost every white majority country, the pillaging and rape of other countries, the opium deal with China, the self-portrayal as pious, the siege of Jerusalem in 1099 where they massacred so many Muslims who were seeking shelter that they (according to reports from even their own side) were eventually wading in blood up to their ankles, segregation in several countries, claiming countries owned by other people as 'no mans land' and then invading and dividing the land up among themselves (British Africa, German Africa, French Africa etc), the list really does go on mate, take your pick.