Once the Balloon Has Gone Up (Origin)
What Is the Origin of the Saying "Once the Balloon Has Gone Up"?Once the balloon has gone up means when trouble is here or in a period of trouble.
The term once the balloon has gone up derives from the First World War. Whenever enemy activity was expected, observations balloons would be released to monitor the enemy troop movements. As a result, the raising of these balloons, which were visible to all, soon became a sign of pending enemy action.