Over and over, the 2nd International and its member parties had warned the workers of the coming war and threatened the ruling classes with their own overthrow should they dare launch Armageddon. And yet in August 1914, the International disintegrated, blown away like insubstantial dust, as one after the other its leaders and parliamentary deputies betrayed their most solemn promises, voted war credits and called the workers to the slaughter.

How could such a disaster happen?