More than 13,000 Conversos were put on trial during the first 12 years of the Spanish Inquisition. Hoping to eliminate ties between the Jewish community and Conversos, the Jews of Spain were expelled in 1492 ..
A second reason, specifically for using Morse Code during the Second World War, was encoding... Nowadays equipment exists to take an outgoing radio signal and automatically encrypt the data or voices during transmission, this is 'on-line' encryption...
During the American Civil War, about 1863 or so. Both sides resorted to it, but it was the machine gun that really made it necessary. In WWI it was a fully developed technique (The Germans, by the way, had much better trenches). By WWII trenches were obsolete due to tanks and aircraft.