Key Point: The M110 could fire a massive eight-inch artillery shell nearly 20 miles away. Even though it’s retired with the United States—Iran still uses it.

M110

The M110 is a bit of a zombie—neither tank nor artillery piece, but something of both. The M110 is based on the smaller M115 howitzer, a towed artillery piece that in its ultimate configuration was designed in 1939, but owed its development to a post-World War I heavy howitzer. 

Both the M115 and the M110 were designed to fire a massive 203 millimeter, or eight-inch, artillery shell a distance of up to 25,000 meters—or more than 15 miles—using standard shells. It could also fire a whopping 30,000 meters—nearly 19 miles—with special rocket-assisted shells.  

Standard high-explosive shells weighed more than 200 pounds and were hydraulically or manually loaded. The M110 was used for counter-battery fire, infantry support, bunker-busting, and anti-armor. They were a beast to load—a neat video shows the M110 being fired by a British artillery unit and shows how highly demanding reloading the big guns was. The M110 was the biggest artillery piece ever used by the United States. 

Though the M110 rides into battle on an integrated hull—essentially a purpose-built tank hull—the entire operating crew does not fit inside, but has to accompany the M110 in another vehicle. The huge 13-man crew includes two loaders, two gunners, an M110 driver, and other crew members. 

Tankless

Though the tank hull appears outwardly similar to any other tank hulls, it is unarmored, and therefore unfit for near-frontline service in a tank destroyer role. Also unlike a tank, the M110 is loaded from the outside, rather than from inside the hull. 

Both the M115 and M110 were able to fire the United States’ W33 nuclear artillery round, a shell that was capable of an explosion equivalent to 40 kilotons of TNT, though of course, Iran does not posses a nuclear-capable artillery shell.

The M110 was introduced into American service during the Vietnam war. It was upgraded in 1977 and given a double muzzle brake and a longer barrel, which increased its range. The M110 saw service as late as operation Desert Storm and the preceding Desert Shield in the early 1990s. They were retired from Army and Marine service shortly afterward and transferred to the Reserves or National Guard units by 1994.

Modest Fleet, Dubious Quality

Iran is thought to maintain a modestly sized fleet of 30 or so M110s, which saw service during the long and bloody 1980-1988 Iran-Iraq War. These platforms probably have a considerable amount of wear and tear, given the likely age of Iran’s M110 platform. Still, they’re bigger than the America’s current big guns.

Caleb Larson holds a Master of Public Policy degree from the Willy Brandt School of Public Policy. He lives in Berlin and writes on U.S. and Russian foreign and defense policy, German politics, and culture. This article first appeared earlier this year and is reprinted due to reader interest.

Image: Wikimedia Commons