tỉnh) and in 1973 changed again its designation to 'Mobile Operations Department' (Vietnamese: Phòng điều hành di động). The basic unit of the Field Police was the company (Vietnamese: Dai Đội – DD), organized into a 24-man company headquarters (HQ) and several 40-man combat platoons (Vietnamese: Trung Đội – TRD), each with four 10-man squads (Vietnamese: Tiệu Đội). Until 1968, one company was assigned to each province and main cities and fielded a number of platoons ranging from two to 13 according to the number of rural or urban districts. For example, up to five districts a single company was assigned, but if a province or town counted more than six districts, two companies could be deployed. After 1969, a major re-organization was implemented, with the provincial companies being expanded to battalions (Vietnamese: Tiệu Doàn – TD). By August 1971, the CSDC strength totaled 16,500 officers and enlisted men organized into 44 provincial battalions comprising some 90 companies, 242 district platoons and one independent armoured cavalry platoon. Two independent companies of four platoons each were based respectively at Vũng Tàu and Da Nang, two autonomous port cities which had their own municipal police services separated from the province in which they were located. To provide supervision and support to all these provincial and urban Field Police units, Regional Headquarters and Service Companies were located at each of the country's four Military Regions. A CSDC company was usually commanded by an Inspector (a Captain after 1971), who came under the operational command of the National Police provincial chief (Vietnamese: Trưởng công an tỉnh) whilst platoons assigned to the districts were firmly under operational control of the district police chief (Vietnamese: Trưởng công an huyện) who, in turn, was directly answerable to the district political chief (Vietnamese: Trưởng phòng chính trị huyện). Armoured car unit A predominantly light infantry force, the CSDC operated a single independent armoured cavalry platoon (Vietnamese: Trung đội kỵ binh độc lập), provided with eight World War II-vintage US M8 Greyhound light armoured cars. Headquartered at Saigon, it was tasked of providing security to the National Police HQ and the adjoining National Bank building and their environs. This unit specialize in combat and patrolling in jungle area, combat and patrolling in urban areas, and maneuver warfare. Tactical Mobile Groups In addition, the Field Police maintained two Tactical Mobile Groups – TMG (Vietnamese: Biêt Doàn – BD) totalling 5,000