The 8 inch (203 mm) M110 self-propelled howitzer was the largest available self-propelled howitzer in the United States Army‘s inventory. Consisting of a M115 203 mm howitzer installed on a purpose built chassis, it was deployed in division artillery in general support battalions and in separate corps- and army-level battalions. Missions include general support, counter-battery fire, and suppression of enemy air defense systems. The M110 was exported to a number of countries.
Additional Information: https://en.wikipedia.org/wiki/M110_howitzer