With its capital in Berlin, Prussia grew from being a small, poor, disregarded medieval state into one of the most vigorous and powerful countries in Europe, the scourge of its many enemies and, ultimately, the motor behind the creation of the German Empire in 1871 with all that implied for the 20th century. After the Second World War Prussia, which had still continued to exist as part of the German state, was abolished by the Allies, blamed for the overwhelming militarism that had led Europe into total disaster. Prussia's role in Europe's fortunes has been incalculable and "Iron Kingdom" is, extraordinarily, the first major book devoted to it. Prussia's power came from a sequence of notably brilliant rulers (most famously Frederick the Great), dynastic marriage and an obsessive focus on military excellence. It was both a progressive, well-run, enlightened country and a huge, threatening barracks. "Iron Kingdom" is a wonderfully readable, gripping account of a state which, for both good and ill, has fundamentally shaped our world.