Slogans related to the prevention of espionage were a common sight during the Martial Law period in Taiwan. In 1950, The “Espionage Prevention Act during the Period for Suppression of Communist Rebellion” was promulgated. Espionage not only referred to Chinese agents hiding in Taiwan, but also included locals who were suspected of treason or political disagreement. Slogans such as “Keeping Secrets to Shield against Spies is Everyone’s Duty” and “Beware, Spies are Among Us” were thus often seen during this period.