The Merchant Marine Defense Medal is a decoration of the United States Merchant Marine. The decoration was established by an Act of Congress on August 14, 1944.
Prior to 1992, the Merchant Marine Defense Medal was a ribbon-only decoration; otherwise known as the Merchant Marine Defense Bar.
On May 19, 1992, the U.S. Department of Transportation announced the availability of new medals for civilian merchant seamen, in recognition of their service in World War II, Korea and Vietnam. The medals are being issued to supplement war zone ribbon bars previously awarded to civilian mariners who supported the nation's armed forces in these wars.