SILESIA. - A historical region of Central Europe, formerly German and now divided between Poland, which comprises almost all of it, and Czechoslovakia, which retains the modest portion (4,423 sq. km. with 800,000 inhabitants) assigned to it by the Treaty of Versailles.
I. GEOGRAPHY
Taken as a whole, Silesia, whose borders are rather ill-defined, extends over about 50,000 sq. km. and essentially embraces the upper Oder basin, from the Sudetes to the Trzebnica Mountains, which separate it from the plains of Poznań and Kuyavia. Its mineral wealth (coal, iron, zinc, lead, nickel) has made it one of the most important centers of heavy industry in Europe.Most of Silesia is divided among the Polish voivodeships of Wrocław (Breslau), Opole (Oppeln), and Katowice. Its population (6-7 million inhabitants in total) is largely concentrated in cities; indeed, seven of these now exceed 100,000 inhabitants: Wrocław, Chorzów, Katowice, Zabrze (Hindenburg), Gliwice, Bytom, and Częstochowa.
II. HISTORY
In the late Roman period, various Germanic tribes were settled there, including the Siling Vandals in the territories of Wrocław, Świdnica, and Niemcza, which later formed the pagus Silensis. The westward migration of Germanic tribes in the 4th and 5th centuries allowed the advance of Slavic tribes. Slavic groupings were present in the region in the 7th and 8th centuries. In the 9th century, Silesia may have been part of the vast Moravian state, and after its collapse at the end of the century, it came under the rule of the dukes of Poland. In the 10th century, the Christianization of the Poles also brought about that of the Silesians; Wrocław became a religious center, perhaps founded by the Czechs in the previous century. Without secure geographical limits, the Oder plain was exposed to the rule of the strongest neighboring Slavic groupings. Under Casimir I (1038-58), when the various Polish tribes were united into a single political entity, the Silesians of the Oder region were also included.At the beginning of the 12th century, Emperor Henry V, in his struggle with Poland, attempted to seize Silesia but was repelled by King Bolesław III (1102-58). When the latter divided his domains among his sons, he assigned Silesia to his eldest son, Władysław. Bolesław intended that the domains of his various sons remain united under the authority of the one who held the central government in Kraków. However, Silesia felt this bond very little and lived under the princes of the Piast dynasty in ever greater isolation. Upon the death of Władysław (1159), Silesia was divided into two duchies: Bolesław received Wrocław, and Mieszko received Upper Silesia. Duke Bolesław founded the Wrocław dynasty with Henry and Henry II; the latter then divided his duchy among his sons Bolesław and Henry III, who founded the dynasties of Legnica and Lower Silesia. These Piast princes in the Oder valley from the 12th century began to feel the influence of Germanism advancing through the parallel efforts of colonists and Cistercian monks. The Silesian dukes encouraged this German infiltration, which seemed economically beneficial, especially after the great Mongol invasion of 1241. When the Mongols withdrew, leaving devastation in their wake, German immigration became massive and soon threatened the Slavic population. The Piast dukes allowed the formation of German communities that settled with their own customs; the dukes exempted them from paying tribute. The cities became Germanized, so that Wrocław became Breslau. In the agrarian transformation of the country, the Cistercian monks distinguished themselves.
The First World War (1914-18) revived the ambitions of the two countries that had dominated Silesia in the Middle Ages: Poland and Bohemia. The Treaty of Versailles (28 June 1919) provided for a plebiscite in Upper Silesia (Oppeln district), where the population was mixed German and Polish. The plebiscite of 20 March 1921 resulted in 705,000 votes for Germany and 479,000 for Poland. The Council of the League of Nations, by a decision of 20 October 1921, assigned to Germany the centers of Oppeln, Gliwice, Zabrze, Beuthen, and to Poland part of the Racibórz district with Rybnik, Pszczyna, and Katowice. The Duchy of Opava (Troppau) was divided between Poland and Czechoslovakia. Of Upper Silesia, Poland received 3,221 sq. km. and Germany 316 sq. km.; of Lower Silesia, Poland received the territories of Reńska Wieś and Bralin with 512 sq. km. The situation in Silesia remained unchanged until the Second World War. After the Soviet occupation, any possible changes remain unknown.