Why was Armed Guards instituted? Were they on every American cargo vessel or just "important" ones? Was there an average # assigned? and was it according to each sailing or each vessel? Did it depend on importance of cargo. Who dictated assignments? Dept of Navy?
At the beginning of World War II, U.S. and Allied merchant ships were unarmed. The British and the Commonwealth nations quickly armed their merchant fleets (and remember the war started much earlier for them than for the U.S.). The U.S. was initially prevented by law, the Neutrality Act, from arming its merchant vessels, even though some U.S. merchant vessels were attacked and sunk, beginning as early as November 1940. The U.S. eventually repealed the Neutrality Act and began the task of arming its merchant vessels, even before the U.S. joined the war. But it took time to arm vessels and train and deploy Armed Guard units on the vessels, and many unarmed or lightly armed U.S. vessels were lost in the early months of the war. The first Armed Guard crew was placed on SS DUNBOYNE on 2 December 1941.
I can't say that EVERY U.S. merchant ship carried an Armed Guard unit (as implied above there was an insufficient number of Armed Guard early in the war) but the vast majority of U.S. merchant ships eventually included Armed Guard detachments. The U.S. Navy Armed Guard even served on some non-American vessels, for example ships under the Panamanian flag that operated under the direction of the U.S. (The British had their own arrangement for arming and manning their vessels.)
The typical Armed Guard complement assigned to a merchant vessel consisted of about 24 gunners, three communication specialists (signalmen or radiomen) and an officer, generally an ensign, lieutenant junior grade or full lieutenant. Some ships, particularly troop transports, carried much larger Armed Guard crews, including two or even three officers, to man the greater number of weapons installed on troop ships. This was the only general case in which the type of "cargo" (troops) dictated a larger Armed Guard contingent. As far as I am aware variations in the type or importance of cargo did not affect the size of the Armed Guard crew, though there may have been exceptions.
The movement of U.S. merchant vessels was directed by the U.S. War Shipping Administration (WSA). I am sure the Navy worked very closely with the WSA in making Armed Guard assignments to each vessel.
Late in the war the number of available Armed Guard sailors apparently exceeded the need, for many Armed Guard men were reassigned to the U.S. fleet (i.e., to warships), where their gunnery experience was invaluable on Navy vessels.
I hope I have come fairly close in giving accurate answers to J.S. If I have misstated or missed anything in my answers, I invite any of the Armed Guard veterans reading this to correct me. You were there, I wasn't.
Ron Carlson, Webmaster Armed Guard / Merchant Marine website www.armed-guard.com
Thank-you Ron, that was very informative & answered all of my questions. Many of my relatives served in this war but I've never heard that term before. Very interesting. Thanks again. Love your site.