Peter Calvocoressi & John Pritchard 
Penguin History of the Second World War [EPUB ebook] 

First published in 1972 under the title TOTAL WAR, THE PENGUIN HISTORY OF THE SECOND WORLD WAR was designed by its authors to show a rising generation why the Second World War happened and how it was conducted. In this bold feat of compression they give as much stress and space to political, social and moral forces (not to mention intelligence and other activities 'behind the line’) as to the ensuing clashes of arms. This acclaimed analysis of the causes and courses of the Second World War has stood the tests of time and criticism.