In World War II, Morse code was sent by light signals. A variation of the original was made by Friedrich Gerke in 1848, which evolved into the International Morse Code.

Wayne Shearer’s World War II Memoir, ... Many of us failed the Morse Code light blinker retake test. We’re being held back for 4½ weeks and will take over all the courses.

Modern warfare is awash with cutting-edge technology – from AI to drones to hypersonic missiles – yet one technology that is more than a century old is still proving its worth: morse code ...