The BGS was established in 1951 after the Cold War had begun but travel between East and West Germany was not yet restricted by the Berlin Wall (1961). When German nationals could move freely from the DDR to the BRD in Berlin, people attempting to cross illegally elsewhere were likely to be either commercial smugglers or espionage agents carrying contraband (e.g., radio transmitters.). Occupation authorities judged this could be better policed by a permanent force of Germans who knew the border woods and mountains intimately (rather than British or US troops who rotated out of Germany after a year or two) and at German rather than Allied expense.