The Merchant Marine’s branch-of-service device for Stewards is the crescent moon, which traces its association with military food and supplies back to Napoleon’s introduction of crescent-shaped bread into the rations for the Grande Armée, while the crescent shape itself was said to be inspired by the defeat of the Ottoman Turks at the Battle of Vienna. Following its adoption by the U.S. Army as the symbol for its Commissary Corps during the Civil War, the crescent began to be used by other military branches and in other nations as a symbol of food and supplies. It is now an internationally recognized emblem of food, rations, and supplies.
Today, the Steward Department’s crescent moon is one of a mere handful devices you might see worn by licensed officers on a Merchant Marine vessel; others include a vertical fouled anchor for Deck Officers (think Line Officers), a three-bladed propeller (Engineers), and a pair of crossed quill pens (Purser). During the heyday of the U.S. Maritime Service, the training organization created to oversee the development of Merchant Marine personnel, other branch-of-service devices included an oak leaf (Supply), lightning flashes (Radio), and a caduceus (Hospital).