World War II was the most devasting war in human history, if we're to rank by casualties in absolute numbers or even in terms of horror. No other war was this gruesome.
There are few people alive today that lived through the war, let alone fought in it. In a couple of decades, this great human tragedy will only exist in history books once the last living memories die with the survivors. So, it falls to the rest of us to remember those times, even though we've never lived them, and make sure nothing like it happens again. Ever.
Neil Halloran wrote and directed this documentary/interactive graphic called The Fallen of World War II, which serves to illustrate the scale of WWII casualties. Using elegant data visualization, Halloran split his 15-minute documentary into three sections: the first examines military deaths, while the second deals with those of civilians (including victims of the Holocaust). The third, however, goes into a different territory showing how infinitely better the world has fared since WWII - an age of peace.