During World War II the government realized that the majority of citizen-soldiers had no idea on how to conduct themselves to prevent inadvertent disclosure of important information to the enemy. Central to maintaining national security was the Office of War Information Drive to limit talk about the war in both public and private arenas of American life. Silence meant security.
As such, great emphasis was placed on educating servicemen and civilians about the need for secrecy concerning military matters and massive advertising campaigns were launched. In fact, the advertising campaign was so large that no other series of World War II posters portrayed such a recurring theme as this. It is from this era that the statement