The 1st Provisional Marine Brigade was created in Charleston South Carolina in July 1941 in a period of 15 days to take over garrison duties from British and Canadians troops in Iceland. US forces comprised the 6th Marine Regiment, 5th Defense Bn., and 2nd Bn., 10th Marine Regiment. The unit returned to the United States in early 1942 where it was disbanded in New York City on 25 March 1942 and resumed its assignment with the 2nd Marine Division. The link is posted below.
http://www.nps.gov/archive/wapa/inde...8-00/sec1g.htm