Prussian economy. It was in the great industrial regions of Prussia that most of Germany's mines, plants and factories were to be found. Prussia's central location on the Continent gave her control over the most important German rivers and trade routes. And it was the Prussian authorities who took the initia­ tive in establishing the customs union which played so important a part in bringing about the economic unification of the country. But the origins of the industrial revolution are to be sought in the second half of the eighteenth century rather than in the nineteenth century. It was the age of Frederick the Great that saw the rise of Prussia not only as a leading military power but also as a manufacturing country. When Frederick came to the throne Prussia had an agrarian economy. Her main exports were grain and timber. The manufacture of woollen cloth in the Mark Brandenburg and the production of metal goods in the

County of Mark were virtually the only industrial activities of more than local importance. As centres of commerce and manu­ factures Berlin, Stettin, Frankfurt an der Oder, Magdeburg and Halle an der Saale could not be compared with Hamburg, Cologne, Leipzig or Frankfurt am Main.