Fatto generale: 1918 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 1918 is an unremarkable number.
Trivia: 1918 is an unremarkable number.
Data storica: April 1st is the day in 1918 that the Royal Air Force is created by the merger of the Royal Flying Corps and the Royal Naval Air Service.