of 10 January 1920 and parts of Prussian Silesia were either annexed by Czechoslovakia (Hlučín Region) or Poland (Polish Silesia), while four congregations of the Rhenish ecclesiastical province were seized by Belgium, and many more became part of the Mandatory Saar (League of Nations). The Evangelical congregation in Hlučín, annexed by Czechoslovakia in 1920, joined thereafter the Silesian Evangelical Church of Augsburg Confession of Czech Silesia. The Polish government ordered the disentanglement of the Ecclesiastical Province of Posen of the Evangelical State Church of Prussia's older Provinces – except of its congregations remaining with Germany. The now Polish church body then formed the (, ), which existed separately from the Evangelical-Augsburg Church in Poland until 1945, when most of the former's congregants fled the approaching Soviet army or were subsequently denaturalised by Poland due to their German native language and expelled (1945–1950). The United Evangelical Church in Poland also incorporated the Evangelical congregations in Pomerellia, ceded by Germany to Poland in February 1920, which prior used to belong to the Ecclesiastical Province of West Prussia, as well as the congregations in Soldau and 32 further East Prussian municipalities, which Germany ceded to Poland on 10 January 1920, prior belonging to the Ecclesiastical Province of East Prussia. A number of congregations lay in those northern and western parts of the Province of Posen, which were not annexed by Poland and remained with Germany. They were united with those congregations of the westernmost area of West Prussia, which remained with Germany, to form the new Posen-West Prussian ecclesiastical province. The congregations in the eastern part of West Prussia remaining with Germany, joined the Ecclesiastical Province of East Prussia on 9 March 1921. The 17 congregations in East Upper Silesia, ceded to Poland in 1922, constituted on 6 June 1923 as (, ). The church formed an old-Prussian ecclesiastical province until May 1937, when the German Polish Geneva Accord on Upper Silesia expired. Between 1945 and 1948 it underwent the same fate like the United Evangelical Church in Poland. The congregations in Eupen, Malmedy, Neu-Moresnet, and St. Vith, located in the now Belgian East Cantons, were disentangled from the Evangelical Church of the old-Prussian Union as of 1 October 1922 and joined until 1923/1924 the Union des églises évangéliques protestantes de Belgique, which later transformed into the United Protestant Church in Belgium. They continue to exist until this very day. The congregations in