Final answer:
The M777 howitzer uses an FMTV truck as its prime mover, which provides mobility and logistical support in military operations.
Step-by-step explanation:
The howitzer that uses an FMTV (Family of Medium Tactical Vehicles) as its prime mover is the M777 howitzer. This towed 155 mm artillery piece is designed for a variety of combat and support roles in modern armies.
In the U.S. Army and Marine Corps, the FMTV trucks are commonly employed to transport the M777 howitzer, which offers significant firepower combined with high mobility and flexibility on the battlefield. The FMTV trucks provide the logistical support to ensure the howitzer can be quickly relocated to support the needs of various military operations.