Technical auxiliary battalion  Technical auxiliary battalions (Pomocné technické prapory [PTP] in Czech, Pomocné technické prápory in Slovak) or Military camps of forced labor (Vojenské tábory nucených prací [VTNP] in Czech) - military camps forced labor) were units of the Czechoslovak People's Army, which served in 1950-1954  in Czechoslovakia for the internment and re-education of those persons which were considered disloyal. These were essentially forced labour camps. An important reason for its creation was also securing cheap labour for selected industries, mainly mining and construction. They were also a tool of persecution and work exploitation of politically uncomfortable persons and class enemies. These included intellectuals ("intelligence"), commoners ("buržoazní původ"), noblemen ("šlechta") and members of the clergy. The functioning of the Technical Auxiliary Battalions was not legally covered by the Czechoslovakian laws in force and by international law. Uniforms of members of these camps had black shoulder boards, so they were colloquially called and known as the “Black Barons”. Although formally assigned to the military, they were not allowed to carry weapons. Instead, they had to do dangerous work in mines or factories. They received no significant remuneration, were treated more like slaves and ruined their health. A number of Czech and Slovak sportsmen, who were labelled as the „unreliable“, also worked, as the “Black Barons”, at constructions projects. Approximately 60,000 Czechoslovak citizens were conscripted to the Technical Auxiliary Battalions, of which "some 400" lost their lives. They worked in the coal mines (in Ostrava and Kladno in the Czech lands, and also in Slovakia), in the construction industry (e. g. Prague settlement of Petriny), on military constructions (airports, barracks, residential buildings and other objects, e. g. military hospital in Prague), in military forests, quarries and agriculture. The last four of the more than 20 camps were dissolved in 1954. The facilities were also supervised by foreign intelligence services. For example, the CIA describes how the 57th Technical Auxiliary Battalion in Smeč no was converted into a Technical Battalion in 1954. As a result, the situation of the former coercive members changed significantly: they received new clothes, were armed as regular members of the army and henceforth had a two-year military service instead of an indefinite duration.