Some naval and one air unit can carry or transport other units. Ships Ships can be boarded from any shoreline by simply moving the rider onto the ship. They may also be boarded from inside a coastal city by right-clicking the unit in the garrison box and selecting from the menu, or using the Load command button when on the main map. Helicopters Helicopters are the only air unit that can transport ground units, and they may only be foot soldiers. To board a helicopter a ground unit must start its turn in a city with the chopper and use the Load command button.