Dehomag was a German subsidiary of IBM with monopoly in the German market before and during World War II. The word was an acronym for Deutsche Hollerith-Maschinen Gesellschaft mbH (English: German Hollerith Machines LLC). Hollerith refers to the German-American inventor of the technology of punched cards, Herman Hollerith.
The technology of punched cards dates back at least to the 18th century when it was used for mass production of woven textiles and later used as a recording and playback system in player pianos. The use of punched cards for recording and tabulating data was first proposed and used by Semen Korsakov around 1805. In 1832 Charles Babbage proposed using similar cards to program and to store computations for his calculating engine. punched card technology was further developed for data-processing by Herman Hollerith from the 1880s. It was used for the 1890 United States Census and for the census work of several foreign governments. Willy Heidinger, an acquaintance of Hollerith, licensed all of Hollerith’s The Tabulating Machine Company patents in 1910, and created Dehomag in Germany. In 1911 The Tabulating Machine Company was consolidated with several others, forming the Computing-Tabulating-Recording Company (CTR). In 1923 CTR acquired 90% ownership of Dehomag, thus acquiring patents developed by them. In 1924 CTR was renamed IBM.
As an IBM subsidiary Dehomag became the main provider of computing expertise and equipment in Nazi Germany. Dehomag gave the German government the means for two official censuses of the population after 1933 and for searching its data.
Dehomag leased and maintained the German government's punched card machines. Dehomag general manager for Germany, Hermann Rottke, reported to Thomas J. Watson in New York. IBM established a special subsidiary, Watson Business Machines, to deal with railway traffic in the General Government during the Holocaust in Poland. The German Transport Ministry used IBM machines under the New York-controlled subsidiary in Warsaw, not the German subsidiary. It was legal for IBM to conduct business with Germany directly until America entered the war in December 1941.