This is a look at the planning, construction and operation of the U-boat bases during WW2, primarily focused on the bunkers rather than the personnel and materials accommodation, although that is discussed as well. It is not a technical history as there aren't blueprints or the like, but there are many photographs from WW2 as well as modern ones, as many of the bunkers still exist, some more damaged than others. The author has sections describing each U-boat base from initial conception through building and then their post-war situation. If the book can be faulted it is that it is somewhat uneven in the content outside of the base descriptions. ( )