How realistically did the British government assess the threat from Nazi Germany during the 1930s? How accurate was British intelligence's understanding of Hitler's aims and Germany's military and industrial capabilities? In The Ultimate Enemy, Wesley K. Wark catalogues the many misperceptions about Nazi Germany that were often fostered by British intelligence. This book, the product of exhaustive archival research, first looks at the goals of British intelligence in the 1930s. He explains the various views of German power held by the principal Whitehall authorities—including the various military intelligence directorates and the semi-clandestine Industrial Intelligence Centre—and he describes the efforts of senior officials to fit their perceptions of German power into the framework of British military and diplomatic policy. Identifying the four phases through which the British intelligence effort evolved, he assesses its shortcomings and successes, and he calls into question the underlying premises of British intelligence doctrine. Wark shows that faulty intelligence assessments were crucial in shaping the British policy of appeasement up to the outbreak of World War II. His book offers a new perspective on British policy in the interwar period and also contributes a fascinating case study in the workings of intelligence services during a period of worldwide crisis.