This book gives the reader an overview of the actions by the German Kriegsmarine during WWII. It does not cover the actions in detail, but presents the reader with the how and why the commanders thought about and fought the actions. It adds the Allied side to the events in some places to make clear why certain things happened the way they did.
Unfortunately I found the Dutch translation a bit clunky and one needs to keep in mind that the book was written in the seventies, so the way of writing is somewhat 'old'. Next to this it is clear that the Ultra was still an unknown factor.