These excellent books are histories of entire wars condensed to a single, easy-to-read volume. Written by reputable historians and similarly formatted: They analyze causes, strategies, and battles in chronological order with maps. This makes them handy reference guides; you can read the whole book, a chapter, or look up a specific phase or battle of the war. You won’t find any foxhole-level descriptions of fighting in these volumes (there are plenty of other books for that), but you will find trenchant critiques of generals and tactics. First publication dates are given.
Civil War: The Compact History of the Civil War, by R. Ernest Dupuy and Trevor Dupuy, 1991, approx. 500 pages (depending on edition)
World War 1: The Real War 1914-1918, by B. H. Liddell Hart, 1930, approx. 500 pages (depending on edition)
World War 2: History of the Second World War, by B. H. Liddell Hart, 1968, approx. 800 pages (depending on edition)