What marks the beginning of the preparation phase in military operations?

The beginning of the preparation phase in military operations is marked by the warning order. This order serves as an early alert to the troops, signifying the intent to prepare for an impending operation. It typically includes essential information such as the mission, the time, and the actions required to ready the unit for upcoming tasks.

The warning order is crucial because it allows units to begin planning and coordinating their activities in anticipation of the deployment or operations that will follow. It helps to establish situational awareness and ensures that all personnel are informed and prepared for the next steps. By initiating the preparation phase, it sets in motion the process of organizing resources, logistics, and training necessary to successfully carry out the mission.