Northumberland, the third-largest English county, may be said to have come into being 900 years ago when, in 1095, King William II deposed its rebellious earl, Robert de Mowbray, and subjected the land between the rivers Tyne and Tweed to the direct rule of the English crown. The kings of Scotland long refused to accept that the county should be English and, as a consequence of this and later quarrels between the two kingdoms, the following centuries saw frequent bouts of warfare and raiding which affected the lives of its people to a degree not known elsewhere, except in Cumberland and the Scottish border counties. All this should have ended when James VI of Scotland became king of England in 1603. But the occupation of the county by a Scottish army during the English Civil War in the 1640s prolonged the border problem. Only with the departure of that army in 1647 did Northumberland cease to be torn by strife. This history seeks to explain and illustrate how life and public institutions in Northumberland developed in such threatening and uncertain circumstances. It should appeal to scholars and general readers alike.