The United States Merchant Marine had its own WWII Victory Medal, with similar themes. This medal was designed by John Sinnock. Lurking near the bottom of the medal is a submarine, which was the greatest threat to Merchant Marine ships.
The Merchant Marine consists of privately owned ships and civilian personnel who can serve as a U.S. naval auxiliary in a time of war or national emergency. These private ships were used to transport cargo and troops during WW2, and other conflicts. Merchant Mariners were civilians but worked under the direction of the US Navy. In 1988, a Federal Judge ordered that Merchant Mariners were entitled to "veterans recognition" which included some benefits.
Suggested reading: Michael Gillen's, "Merchant Marine Survivors of World War II," 2014