Schleswig-Holstein, a province of Prussia, formed in 1866, and consisting of the former duchies of Schleswig and Holstein, bounded N. by Denmark, E. by the Baltic, Lübeck, and Lauenburg, S. by the province of Hanover, from which it is separated by the Elbe, and W. by the North sea; area, 6,766 sq. m.; pop. in 1871, 995,873, chiefly Protestants. The inhabitants are a mixture of various races. In N. Schleswig Danish is spoken by about 145,-000 people, who occupy nearly half of the former duchy of Schleswig. In S. Schleswig and Holstein nearly all the inhabitants speak German. The Frisian dialect is still spoken in some of the western parishes, but it is not used in either church or school. The district between and E. of the towns of Schleswig and Flensburg is known as the territory of the Angles. The province constitutes only one administrative district, called Schleswig. The principal towns are Altona, Kiel (the capital), Rendsburg, and Glückstadt in Holstein, and Schleswig and Flensburg in Schleswig. The chief rivers, besides the Elbe, are the Eider, which separates Schleswig from Holstein, the Trave, and the Stör, an affluent of the Elbe. A number of islands lie opposite the W. coast of Schleswig, of which Römö, Sylt, and Föhr are the most important.

The islands of Alsen in the Little Belt and Femern N. E. of Holstein also belong to the province. The surface is mainly level; in the interior of Schleswig there is a slightly elevated sandy ridge covered with heath, which increases in height toward the north. The soil of Holstein is very fertile, and produces wheat, buckwheat, potatoes, hops, hemp, flax, and wood. The soil in the interior of Schleswig is light and stony; the W. side is bordered by a strip of rich marsh land, and artificial dikes and sluices are necessary to prevent its being overflowed. The province is noted for its fine horses, which are famous for heavy cavalry service and are exported in considerable numbers. The manufactures are not important; only Neumün-ster in Holstein can be called a manufacturing town. (See Holstein.) - In 1386 the counts of Holstein received Schleswig as a Danish fief. Their line becoming extinct, the estates of Schleswig-Holstein in 1460 elected Count Christian of Oldenburg to be their sovereign, who had in 1448 been chosen king of Denmark. It was stipulated that the duchies "should for ever remain together undivided," and the estates reserved the right to choose at any time a successor from among his descendants.

The agreement to maintain the integrity of Holstein was soon broken, and in 1490, with the consent of the estates, two sovereign houses were founded. These were united again under Frederick I., but in 1544 three sovereign houses were founded. Since 1580 there have been three main branches of the family of Schleswig-Holstein: the royal Danish, called the Holstein-Glückstadt; that of Holstein-Gottorp, of which since 1762 the czar of Russia is the head; and the Holstein-Sonderburg, which had no territorial authority. In 1616 the estates yielded their right of election, and the law of succession became that of primogeniture, with reversion to the collateral branches. In 1773 the future emperor Paul I., as duke of Holstein-Gottorp, ceded all his possessions and claims in Schleswig-Hol-stein to the king of Denmark, in exchange for the principality of Oldenburg, which he transferred to the youngest branch of the Holstein-Gottorp family. The ancient constitution of Schleswig-Holstein had since the 17th century fallen into abeyance, and in 1802-'6 the estates were formally abolished.

In 1815 the king of Denmark had to enter the German confederation as duke of Holstein, and in 1823 the inhabitants of that province appealed to the German diet for the constitution of 1460, without effect; but in 1834 chambers were erected both for Schleswig and for Holstein. But still the repressive measures of the government, and a persistent effort to bring the German language into disuse in the churches, schools, and courts, created discontent. The Salic law had never prevailed in either Schleswig or Holstein, and the royal house in the male line was about to become extinct when on July 8, 1846, appeared a proclamation of the king, extending the Danish laws of succession to all his dominions except a part of Holstein, at the same time expressing the intention of including even this in time. The collateral branches of the reigning family, the estates of the duchies, and the German diet protested; but on March 24, 1848, Frederick VII. proclaimed the incorporation of Schleswig with Denmark. This was the beginning of a three years' war, in which the duchies contended for their independence, and were for a time aided by Prussia. (See Denmark.) In January, 1851, Austria and Prussia jointly intervened, disbanded the Schleswig-Holstein army, and on Feb. 18, 1852, surrendered Holstein to Denmark. At the London conference of May, 1852, the great powers and Sweden fixed upon Prince Christian of Schleswig-Holstein-Sonder-burg-Glücksburg as the next king.

The other branches of the prince's family residing in Denmark renounced their claims in Prince Christian's favor, but those residing in Schleswig-Holstein did not. Neither the estates of the duchies nor the German diet became a party to this agreement. In 1854 constitutions were granted to both Schleswig and Holstein; but they were not satisfactory to the people, and in November, 1863, the parliament formally incorporated Schleswig with Denmark. In the same month the king died, and, in accordance with the London treaty? the prince of Sonder-burg-Glücksburg ascended the throne as Christian IX. The prince of Schleswig-Holstein-Sonderburg-Augustenburg, whom the duchies regarded as the rightful heir, proceeded to Kiel to assume the government. In the mean time the German diet had declared the treaty of London broken by Denmark, and an Aus-tro-Prussian army entered Holstein. After severe fighting the Danes were driven out of Schleswig, and even Jutland was occupied by German troops. England attempted in vain to mediate, a second London conference came to nothing, and the Danes were completely subdued.

At the treaty of Vienna, Oct. 30, 1864, Christian IX. renounced all his claims to Schleswig-Holstein, and also to Lauenburg. The convention of Gastein, Aug. 14, 1865, assigned the occupation of Holstein to Austria and of Schleswig to Prussia. After the war of 1866 both duchies came under Prussian rule, and were shortly after made a province of the Prussian monarchy. The article in the treaty of Prague between Austria and Prussia, providing for a restoration of Danish-speaking Schleswig to Denmark should the people vote for it, has thus far (1875) been disregarded. (See Denmark.) - See Droysen and Samwer, Die Herzogthümer Schleswig-Holstein und das Königreich Dänemark (2d ed., Hamburg, 1850); Lüders, Denhwürdigkeiten zur neuesten schleswig-holsteinischen Geschichte (4 vols., Stuttgart, 1851-'3); Baudissin, Geschichte des schleswig-holsteinischen Kriegs (Hanover, 1862); Rüstow, Der deutsch-dänische Krieg von 1864 (Zürich, 1864); Der österreichisch-preussische Krieg gegen Däemark (Vienna, 1865); and Möller, Geschichte Schleswig-Hol-steins (2 vols., Hamburg, 1865).