Book excerpt: No Room for Mistakes is a thoroughly researched account of British and Allied submarine warfare in north European waters at the beginning of World War II. Haarr has compiled research from a wide range of primary sources to create one of the most readable, comprehensive accounts of early war submarine activities. With detailed, accurate maps and many previously unpublished photographs, No Room for Mistakes documents the birth of a new kind of war and the courage of the men who learned to fight it.