Leadership Development Step by Step- What Makes a Successful Leader is one of the few books that can be a driving force to make people prepare others for the future. The British government coined the slogan “Keep Calm and Carry On” in 1939 as the threat of World War II loomed was the inspiration behind the book. In the event where Hitler’s army invaded England, the posters were to be distributed to England’s general population to galvanize their resolve to resist German aggression.