To say that that the First World War was the greatest cataclysm in human history since the fall of the Roman Empire is to put it mildly. The war destroyed so many good things and killed so many good people that civilization has not recovered and probably never will. Long after it officially ended, it continued to cause millions of deaths and tragedies, most obviously during its encore performance of 1939-45. But it did not stop even then. Many of its worst consequences came during official periods of peace and are unknown or forgotten, or remain unconnected with it in the public mind.
Source: The American Spectator.