Source: Review of To Hell and Back: Europe 1914–1949, by Ian Kershaw, and other books in The New York Review of Books, April 7
In the war of the Triple Alliance of 1864–1870 between Paraguay and its neighbours, ninety percent of the male population of Paraguay perished.
WW1 began August 1, 1914. By the end of November, British losses were already at 890,000, more than had been initially recruited to fight.
During the first nine months of the war, Russia lost just under two million men of whom 764,000 were captured.
British and Dominion troops lost 57,470 men in the first day of the Battle of the Somme
Austrians summarily executed at least 3,500 Serbian civilians.
In the Spanish civil war, more than a million, out of a population of 25 million, suffered death, torture or imprisonment.
110 out of 139 members of the Central Committee of the Communist Party were executed by Stalin during the Terror of 1936–38.