The Evolution of Germany by John A. Hawgood
Originally published in 1955, this book concisely charts the development of the states of Germany backwards, from the post-war partition into two republics, through the ruthless unification imposed by Hitler and the efficient federation created by Bismarck to the acute disunity of the 400 separate sovereignties existing in Germany after the Peace of Westphalia. The book also covers regional and geographical differences, natural resources, the class system and population problems.