World's End - 1940. by Upton Sinclair, author of The Jungle (1906). PermaBooks 1960.

Between 1940 and 1953, Sinclair wrote a series of 11 novels featuring a central character named Lanny Budd. The son of an American arms manufacturer, Budd is portrayed as holding the confidence of world leaders, and not simply witnessing events, but often propelling them. Sinclair placed Budd within the important political events in the United States and Europe in the first half of the 20th century. 

This book is the first novel of the series. First published in 1940, after World War II had begun in Europe the previous year, the story covers the period from 1913 to 1919, before and after World War I.