This might be the definitive command history of the U-Boat campaign in the first half of WWII. The book is in 2 parts, the campaign vs the British Empire to December 1941 and the campaign vs the Amercas to December 1942. It is a monumental work; 700 pages without the appendices. The book documents every important U-boat voyage and, on many voyages, accounts for every torpedo expended. This is a command history focusing on combat actions and tactics. There is less emphasis on human factors such as the experiences and perspectives of the crews of the U-Boats, escorts and merchantmen. For example, there are few quotations from first hand accounts. This stands in the way of the book being the definitive history of the campaign.
The author was a submariner in the US Navy in the Pacific in WWII. He provides refreshing and frank assessments of British and German decisions and capabilities. There is a more partisan tone to his treatment of USN leaders and decisions. He is concerned to bolster the reputations of the USN and its CinC Admiral King vis a vis British criticism, decisions by President Roosevelt and the rivalry of the US Army Air Force. The book fully integrates an account of the intelligence war and code breaking with the combat actions of the U-Boat campaigns. This is a great strength. There are many other fascinating pieces of information: how the Germans solved the problem of faulty torpedoes by copying captured British models; how the much vaunted Type VII U-Boat design to took several years and versions to 'de-bug'; and the disproprtionate importance of a cadre of aggressive and experienced U-Boat captains to the tonnage war.
The analytical component of the book is overshadowed by the length and detail of the chronological narrative. However by providing such a fulsome knowledge of U-Boat operations the book allows the reader to form their own judgements about many of the factors in the U-Boat war. There are useful chapter headings to guide the reader and comprehensive indexes. One quibble; the bibliography, which I assume from the research would be excellent, is only in the second volume covering the second half of the war. The weight of detail makes this a work for those with a keen and established interest in the subject; and for those readers it is a mine of information.