John Eppstein 
How the World Changed [PDF ebook] 

First published in 1969, this two-volume set was written specifically for those with little or no prior knowledge of twentieth century world history. Together the volumes outline the main political history of the period, including the end of the Victorian age and the break-up of the nineteenth century Concert of Europe; the two World Wars and their consequences; the Russian Revolution; and the rise of the United States of America as a world power. The first volume covers 1900-1939 and the second volume covers 1939-1968.