zero hour

• Moment critique prévu pour le début d'une opération ou d'un événement important ; heure fixée pour le lancement d'une action planifiée.

The critical moment when an important event, operation, or decision is scheduled to begin; the time set for the start of a planned action.

1. Critical momentB2formal

   The time when an important event or action is scheduled to begin; the decisive moment.

   heure H

   • Zero hour for the attack was set at dawn.
   • The team waited nervously for zero hour to launch the product.
   • At zero hour, the countdown began for the rocket launch.

2. Military operation startC1formal

   The exact time designated for the start of a military operation.

   heure H

   • The general ordered the troops to be ready by zero hour.
   • Zero hour was postponed due to bad weather conditions.
   • All units must be in position before zero hour.