Making collective arrests outside Bab al-Zahirah (Herod's Gate), Jerusalem, September 1938. The British held 816 Palestinians in detention camps in 1937, and 2,463 in 1938. In 1939 they detained 5,679 Palestinians out of a total Palestinian population of ca. one million. This would be roughly equivalent to detaining 1,283,454 Americans, on the basis of the current United States population of ca. 226 million.