In preparation for the peace conference that was expected to follow World War I, in the spring of 1917 the British Foreign Office established a special section responsible for preparing background information for use by British delegates to the conference. Austrian Silesia is Number 4 in a series of more than 160 studies produced by the section, most of which were published after the conclusion of the 1919 Paris Peace Conference. The duchy of Austrian Silesia consisted of the two Silesian districts of Troppau and Teschen that remained under Austrian sovereignty after the conquest of Silesia by Frederick the Great of Prussia in 1742. The remainder of Silesia had been ceded to Prussia by Empress Maria Theresa of Austria in the Peace of Breslau of June 1742. The book includes sections on physical and political geography, political history, social and political conditions, and economic conditions. According to the census of 1910, the population of the duchy was made up of three main ethnic groups: Germans (43.90 percent), “Czecho-Slovaks,” i.e., Czechs (24.33 percent), and Poles (31.72 percent). These groups mainly lived in geographically distinct districts and had complex relations with each other. With the breakup of Austria-Hungary at the end of World War I, most of Austrian Silesia became part of the newly created state of Czechoslovakia.