U.S. Army shoulder patches have had a short but colorful history of serving as insignia for military units. In 1918 a U.S. Army unit the 81st Division wore the first shoulder sleeve patch into battle. Soon after, other units going to battle in World War I were also wearing insignias and patches as unit identifiers. Since then shoulder patches worn on the left shoulder are used to identify membership in a particular unit. A shoulder patch worn on the right shoulder is a badge of honor that readily identifies a soldier as having served in a combat zone with a particular unit. Some soldiers proudly wear the same combat patch for the rest of their Army careers.