In 1951 the West German government established a Federal Border Protection Force ("Bundesgrenzschutz" or BGS) composed of 10,000 men under the Federal Interior Ministry's jurisdiction. The force replaced allied military organisations such as the U.S. Constabulary then patrolling West Germany's borders. The BGS was described as a mobile, lightly armed police force for border and internal security despite fears that it would be the nucleus of a new German army. When West Germany did establish an army, the "Bundeswehr", BGS personnel were given the choice of staying in the BGS or joining the army. Most decided to join the army.