“Keep Calm and Carry On” is repurposed propaganda.
The popular “Keep Calm and Carry On” slogan was originally created by the British government as a form of propaganda to urge citizens to stay civil during World War II, when London frequently endured air raids from Germany.
Alas, it never caught on. Years later, in the 2000s, a poster was discovered, and many companies have used it as a slogan or marketing theme for their products. Apparently, vintage sensibilities apply to modern public relations campaigns too.