Paul Michael Kennedy is a British historian specialising in the history of international relations, economic power and grand strategy. He has published prominent books on the history of British foreign policy and Great Power struggles.
Great book on the limits democracy places on the freedom of action of a government's foreign policy and military apparatus. One area particularly relevant to the US today is the period of the 1865-1914 and particularly 1969-1890 when the government swung back and forth many times without policy continuity, because the public could not form a consensus around a "little England" policy and imperial ambition. This is not unlike what we are seeing in the US today with a 50-50 nation.