Westphalia, a name given to a duchy and a kingdom, and now to a Prussian province, is derived from the Westfalen, a western tribe of Saxons, dwelling in the region of the Ruhr and Lippe rivers, as distinguished from the Ostfalen, nearer the Elbe. About 1180 it came under the Archbishops of Cologne, as Dukes of Westphalia. It was the headquarters of the Vehmgerichte (q.v.). Under the Emperor Maximilian part of old Westphalia with parts of Oldenburg and Hanover was made a 'circle' of the empire; while the duchy fell into the circle of the Lower Rhine. In 1801 all the country west of the Rhine was made over to France, and the duchy granted to the Duke of Hesse-Nassau as compensation for his losses to the west of the Rhine. In 1807 Westphalia, with parts of Hesse, Hanover, Brunswick, and Saxony, was made into a kingdom for Jerome Bonaparte, and designed to be the centre of the Confederation of the Rhine (q.v.). In 1813 the kingdom came to an end, and the Congress of Vienna assigned the present province of Westphalia to Prussia. This province has an area of 7892 sq. m. (larger than Wales) and a pop. (1890) of 2,423,661, of whom 1,145,627 were Catholics. The northern portion belongs to the great north German plain, and is not fertile; the south is hilly, with fertile valleys. Westphalian hams are still in high repute; but Westphalia's peculiar wealth lies in its mineral treasures—iron, zinc, copper, sulphur, with lead, antimony, &c. Iron-working is largely carried on, and linen-weaving has been an important industry since the 14th century—Bielefeld being the great centre. Münster has cotton-works.
The peace of Westphalia, concluded at Münster and Osnabrück 24th October 1648, brought the terrible Thirty Years' War (q.v.) to an end. The main advantage to the Protestant party was the securing of religious toleration. Both parties agreed to abide by the distribution of territories as at 1624. The Lower Palatinate was restored to the son of the Elector Palatine; the Upper Palatinate to Bavaria. Part of Alsace was definitively ceded to France; western Pomerania, Bremen, and Verden fell to Sweden, which in virtue thereof became a member of the Holy Roman Empire. Brandenburg and Hanover obtained some secularised church lands; and the independence of Holland and Switzerland was formally recognised. The sovereignty of the different states of the empire was recognised to an extent that seriously weakened the strength and unity of the empire.