Central European republic formed in 1918 from elements of the Austro-Hungarian Empire. It comprised Bohemia and Moravia, Slovakia, Austrian Silesia and the Sudetenland, which had a largely German population. This failure of Austrian authority in 1918 affected all aspects of life in Czechoslovakia, including the postal service, which had stopped operating even in the large cities. In Prague a local post was operated by Boy Scouts under the control of the Revolutionary Council. By 1919 the postal service began to return to normal and general issues appeared. Stocks of Austrian stamps found in the Post Offices were overprinted for sale in Czechoslovakia and were sold at a premium to support various charities.
1939 saw claims and counter-claims on various internal territories. Disorder was fermented by Germany and in January 1939 self-government was granted to Slovakia and Ruthenia within the federal area. Slovakia also declared full independence on 14 March and, on the same day, Germany marched into Bohemia and Moravia. Slovakia remained an independent stamp-issuing territory under German control until 1945. Bohemia and Moravia used overprinted German stamps initially and remained a German protectorate until 1945.From 1945 the reconstituted republic issued its first stamps and normal postal services were quickly resumed. Mass Protests in November 1989 led to the resignation of the Communist Party Central Committee and totally free elections were held in June 1990, in which the Communists were defeated.In late 1992, the leaders of the Czech and Slovak republics agreed to dissolve the federation and form two sovereign states. This move became effective on 1st January 1993.
We recommend the excellent stamp listings in the Stanley Gibbons Part 5 catalogue, also the Michel Volume 1 Mitteleuropa catalogue, and excellent POFIS Ceskoslovensko 1918-1939 and 1945-1992 specialised catalogues.