The Battle of the Atlantic has been called the longest battle of WWII, which makes it possibly the longest single battle of all time (depending on how you define "battle" of course). Thus, it is normal for scholarly works to tackle parts of it at a time, which is what this book does with some success. Thus, if the main title "U-Boats Against Canada" is a bit of a misnomer, the subtitle "German Submarines in Canadian Waters" accurately and completely describes the scope of Michael Hadley's work. Any kind of action by or on a U-boat that occurred in Canadian waters are detailed in the book, whether against Canadian, British, American or other Allied forces. A quick glance at the index and the references will show the reader that this is a scholarly book - fully referenced and cross-checked (when possible) between German, British, Canadian, and American sources, where appropriate.
That's not to say that this is a dry read, or one that only academics will be interested in. The writing is engaging, switching between statistical analyses and personal stories of the U-boat captains/crews and the crews of their targets. Most engaging are perhaps the stories of the espionage missions (where spies and equipment were landed on Canadian and American shores from U-boats), since they are so little documented in other military histories (that tend to neglect intellegence operations, especially "routine" ones like setting up weather stations in hostile territory). Many (most?) of these stories will be unfamiliar to the average Canadian, even one with an interest in the era's history (like me!). Larger strategic-level works tend to neglect isolated missions (especially failed ones, such as the capture of the U-boat-landed spies after a mere few days on Canadian soil), and therefore the limited (but not less intense)number of missions in Canadian waters are not given much space in most accounts of the Battle of the Atlantic.
The degree of operational control exerted by the Kriegsmarine in WWII means that declassified/captured German documents and logs are a treasure trove for the dedicated and German-speaking historan; Prof. Hadley meets both criteria. Therefore, you get the feeling that you are reading what is now, and is likely to remain, the definitive account of this aspect of the Battle of the Atlantic. True, this isn't a complete blow-by-blow account of every operational event, but such a compendium would be unreadable to the lay reader, and is not necessary (and would perhaps even be detrimental) to understand and appreciate the nature of warfare on Canada's east coast in WWII. As historians are wont to do, the author also includes some commentary on lessons learned (or not!) and their relevance today. Even though the book is 20 years old now, little has changed with Canada's naval capacity, so any lessons apply equally today as they have over the last 30 years.