After the 1941 attack on Pearl Harbor, American men enlisted and faltering wartime factories called on women to help build aircraft and ships, among other jobs. Women workers filled a crucial void and broke gender barriers when the nation's men were off at war. Nicknamed "Rosies" after one of the first women to work in a defense factory, the women were immortalized in a poster of a worker flexing her muscles with the slogan "We Can Do It."