I bought both books when I was in the States and have read them several times. Their sheer volume almost ensures they are the last word on the history of the U Boat War in the Atlantic, with appendices to cover literally every aspect of the conflict. Unfortunately facts alone don't make a definative history. Having written what is surely the best account of the Pacific submarine conflict, Blair does not seem capable of producing an unbiassed account of the Atlantic conflict. His previous history as a serving U.S.Submarine officer seems to have blinded him to the the facts of the Atlantic campaign and in my book, he lets his bias get in the way and fatally spoils what should have been his finest work.
Literally from the start he adopts an myopic pro American stance. He cites the "So called Battle of the Atlantic" (not really a sub war compared to the Pacific) and as someone who lost relatives in this so called battle, I found his remarks deeply offensive. He then denegrates almost every aspect of the conflict which was not of American origin. German U Boat advances in the Type XX1, (more of a sieve than a sub) then Canadian Escort tactics then British Code breaking and computer building efforts and really goes over the top in support of the theory that the American Admiral King was fully justified in doing absolutely nothing when the U Boats were slaughtering ships within sight of the American coast, especially when he agreed with Michael Gannon in his book "Black May" that King was in dereliction of his duty. Why the volte face? Not one of his better efforts.