The military has strict flag etiquette for every kind of situation, especially in regards to military convoys. This can be for formal occasions and for safety during movement of vehicles and supplies.
Safety and Identification
When a convoy is moving on public roads, there are certain procedures in place that ensure efficient and safe movement of vehicles, troops and supplies. The flags placed on vehicles can be for communication and identification of specific vehicles within the convoy.
According to the U.S. Department of Transportation, the first convoy vehicle is fitted with a blue flag and the ending one with a green flag. A black and white flag is placed on the unit, march and column commanders' vehicles while the trail party vehicle has an orange safety flag. This ensures that the end and beginning along with key personnel vehicles are easily visible to all.
Lead and Trail Vehicle Placement
Setting the pace for the convoy, the lead vehicle has the 12-by-18-inch blue flag with the words "convoy follows" while the last vehicle is mounted with a green one the same size stating "convoy ahead." These are placed on the left rear or front of the vehicle but must be out of the driver's line of sight. This is also the same placement for the trail vehicle sporting an international orange flag.
Other Convoy Vehicles
The commanders' vehicles have the white and black flag on the front left bumper. MP vehicles and those of local law enforcement serving as escorts may not fly convoy identification flags. "Convoy ahead" signs aren't placed on medical and maintenance vehicles unless they are serving as the last one in the convoy.
Flags identifying convoys help keep the march of vehicles in order and to identify key vehicles within the convoy. It also ensures the safety of both the soldiers and the civilians on the road as the convoy moves through.