“Keep Calm and Carry On” is a catchphrase that originally appeared on a World War II-era British public safety poster. After one of the original posters was recovered and placed in a British bookshop in 2000, the inspirational message was shared online, sparking a series of image macros centered around the phrasal template “Keep Calm and X.
The “Keep Calm and Carry On” poster was commissioned in 1939 by the temporary Ministry of Information in England, following the printing of two other inspirational posters stating “Freedom Is In Peril. Defend It With All Your Might” and “Your Courage, Your Cheerfulness, Your Resolution Will Bring Us Victory.” It was intended to be used to strengthen morale in the event of a large-scale attack or occupation, which many considered inevitable at the time.
Source: Walter K.