Croätia and Slavonia (Hung. Horvát-Szlavonország) form, together with their former 'Military Frontier,' a crown-land belonging to the Hungarian section of Austria (q.v.), lying between the Adriatic Sea on the SW., where Croatia has a seaboard of about 84 miles, and Hungary on the NE. Area, 16,352 sq. m., of which 5246 is Croatian, 3707 Slavonian, and 7399 belongs to the district of the military frontier. Pop. (1881) 1,892,499, Croatia having 816,802, Slavonia 377,613, and the former Frontier 698,084 inhabitants; in 1890 the total population had increased to 2,200,977. The surface of Croatia falls mainly into the wooded mountain district to the north of the Kulpa, with offshoots from the south-east Alps, and a calcareous plateau, belonging to the Karst region, to the south. To the Alpine system belong the Matzel, Ivincica, and Kalnik groups in the north; to the Karst system belong the Liburnian Karst (5007 feet), along the coast from Fiume to Novi, and the Velebit Mountains to the south-east, with the peak of Sveto Brdo (5751 feet) near the Dalmatian frontier. The province belongs to the basin of the Danube, its most important rivers being the Drave and Save, with their affluents; the Gatschka, Likka, and others belong to the Karst, and the Zermanja, in the south-west, flows into Dalmatia. In Slavonia extensive marshes are found along the main rivers. Warm mineral springs are numerous, and earthquakes, especially about Agram (q.v.), are frequent. The Adriatic coast is poorly supplied with harbours, and exposed to the blasts of the Bora (q.v.). The climate along the coast and in the north is mild, Fiume and Agram having respectively a mean temperature of 60° and 52° F.; in the Karst the yearly mean is from 43° to 46° F.
The soil is in general very productive. Corn, maize, pulse, millet, flax, hemp, tobacco, and grapes are cultivated; large quantities of wood are exported, the rich forests being for this industry recklessly despoiled; and horses and cattle are successfully raised, while the oak-forests of Slavonia support great droves of swine. Silk-culture is progressing, and bees are largely kept in the heath districts. Only in ores and minerals is the province poor; iron, silver, copper, lead, zinc, sulphur, and coal are all worked, but in small quantities. Much of the weaving is done at home, and the other manufactures are not important. The trade is chiefly in land products, Slavonia exporting also a brandy made from plums. The bulk of the people are Slavs; both Croats (originally Chorvats, 'mountaineers,' from chora or gora, 'a mountain') and Slovenes are tall and strong, honest, and good-natured, holding much of their land in common, and dwelling for the most part in scattered hamlets. In the west the religion is Roman Catholic, embracing 71 per cent. of the entire population; in the east, that of the Greek Church. Education is very backward; in 1890, 40 per cent. of the male inhabitants could neither read nor write. A number of railways, however, now penetrate the country, and the interest in education and in the national language and literature is visibly increasing.
Croatia and Slavonia were for the most part included in the Roman province of Pannonia; in the 7th century the territory was taken possession of by the Slavonic races. The Croats shook off the Byzantine yoke about 900, and in the following century extended their rule over Dalmatia, built a strong fleet, which they employed first for piracy, and afterwards for trade, and had their king, Dirzislav, recognised by the Eastern court in 994. His son, Crescimir Peter, one of the greatest national heroes, was acknowledged as king of Dalmatia, as were also his successors until 1091, when the kingdom was taken over by Hungary. Slavonia was made a province of Hungary about the same date, but in the 17th century a great part of the land was held by the Turks, who only in 1699 resigned all territory north of the Unna. Croatia, Slavonia, and Dalmatia were united as the kingdom of Illyria from 1767 to 1777. Afterwards Croatia and Slavonia were regarded as part of the kingdom of Hungary; but among the Croatians a feeling of hostility to the Magyars grew up, which asserted itself in 1848-49. In reward for Croatia's services during the Magyar revolt, it was declared independent of Hungary, and practically so remained until 1868, when the connection with Hungary was restored, Croatia sending deputies to the Hungarian diet. There must be a Croatian in the Hungarian ministry; there is a national diet at Agram, and the official language is Croatian. In 1883 there was a popular move- ment, with riots, directed against the subordination to Hungary. The Military Frontier, established along the Turkish border in the 16th century, arose out of the necessity of perpetual defence. It was inhabited by military colonists who enjoyed special privileges, maintained regular armed posts, and were able to raise a force of 100,000 men on the briefest notice. This region was in 1881 finally incorporated with Croatia and Slavonia. See BAN; and for language, SERVIA.