The baseplate had long handles on either side to make it easier to carry; it weighed 175 pounds (79 kg).

[3] Upon the entry of the United States into World War II, the U.S. Army decided to develop a high explosive round for the mortar so that it could be used in a fragmentation role against enemy personnel.

Subsequently, the mortar proved to be an especially useful weapon in areas of rough terrain such as mountains and jungle, into which artillery pieces could not be moved.

Before the invasion of Peleliu in September, 1944, the U.S. Navy mounted three mortars each on the decks of four Landing Craft Infantry and designated them LCI(M).

They provided useful fire support in situations where conventional naval gunfire, with its flat trajectory, was not effective.

Sixty LCI(M) were used during the invasion of Okinawa and adjoining islands with Navy personnel operating the mortars.

Mustard gas was not used in these wars and the U.S. ended up with a large number of these shells, declaring over 450,000 of them in stockpile in 1997 when the Chemical Weapons Treaty came into force.

Destruction efforts to eliminate this stockpile are continuing with a few of these aged shells occasionally found to be leaking.