Wars, assassinations, atrocities—these words appeared often in the twentieth century. No earlier century had witnessed as much killing. Population increases provided more people to kill; technological developments provided more efficient means to do so; and expanding media coverage informed more people about such killings and horrors as the century proceeded.

History books, however, are better at providing mind-numbing statistics regarding all this killing than they are at conveying much feeling for the millions of individual tragedies caused by it. The British novelist Ian McEwan hinted at this problem when he wrote about one of his characters:

Some feeling for all these tragedies is also sometimes conveyed by firsthand accounts. A few early ones are provided here, and readers can only attempt to imagine some of the other millions of tragedies which lie behind the gruesome statistics of the remainder of the century.