In 1462 the throne of the Principality of Moscow passed to Ivan III (1462–1505), who succeeded in throwing off the Tatar yoke. For the next 200 years this new state struggled to maintain her borders against a series of attacks from the Lithuanians, Swedes and Poles to the west, as well as the Tatars to the south. They achieved this through the development of a network of fortified sites and a series of linear defensive systems. This book examine how these fortifications were developed to respond to ever changing situations under the command of such charismatic rulers as Ivan the Terrible, right through to the military reforms of Peter the Great.