August 1914 by Alexandr I. Solzhenitsyn

August 1914, as the author says in the beginning, '. . . comprises only the first part, or fascicle, of of a work in many parts. Therefore, it makes no pretense at completeness, even in the development of its characters: except for the operations of Samsonov's army, this is only the initial presentation of a larger work. The whole work, however, may take as long as twenty years, and probably I will not live to finish it. Given the difficulty of retelling history, I need, as the work progresses, the cooperation of readers who still remember the period. That is why I have decided to publish in fascicles, or a series of volumes'. This proves to be true, as it leaves several loose ends with characters and subplots, and I'm not quite sure what book comes next; it may be November 1916.

This book centres on the campaign of the Second Army, in the area of Tannenberg, Prussia, during, as the title indicates, August 1914. The Second Army is led by General Samsonov, a rather pathetic, plodding character from which reality is withheld by those below him in rank. A few characters are introduced near the beginning of the book who have nothing to do with the army, but are mostly peasants on the steppes. These are the loose ends of the book, seemingly forgotten throughout and reintroduced in the last few chapters. 

An officer from General Headquarters is sent to Second Army to assess the situation, a certain Colonel Vorotyntsev, who ties most of the very segregated subplots together. He is young and uncorrupted by rank and achievements, and belongs to a very small group of characters that can actually be related to. 

The campaign is quite complex and would take a more lengthy explanation than I can give, but Solzhenitsyn does it quite clearly, though it takes 622 pages, making August 1914 the second-longest book I have ever read, bested in length only by War and Peace. It is also one of the best I have ever read.

I will also note that my edition had a map of the area of Tannenberg as an insert, without which the plot would have been entirely lost to me.