| Original caption: “Mortar crew firing at Jap[anese] positions on Bougainville during the April assault by members of D Company, Eighty-Second Chemical Battalion, and the weapon is the 4.2 inch mortar.” Mortarmen of D Company, 82nd Chemical Battalion, service the M2 4.2 inch (107 millimeter) chemical mortar during the Battle of Extension of the Perimeter. Unlike most mortars, the M2 “four-deuce” Mortar had a rifled barrel to impart a spin to its projectile, increasing accuracy. The weapon was composed of 3 parts — the 175-pound baseplate that sat on the ground and absorbed the recoil of firing, a barrel 40.1 inches (101.9 millimeters) long, and the “standard.” The standard is connected to the baseplate by 2 connecting rods and has a single vertical piece that houses the elevating mechanism. The mortar is also equipped with an optical sight that lines up on aiming stakes similar to artillery. The entire assembly weighs 330 pounds (a 150 kilograms). The weapon could traverse 7 degrees to the left or right, and elevation was between 105 degrees. Up to 20 rounds per minute could be fired for short periods, though this was often exceeded in combat. Minimum range was 600 yards. Maximum range, initially just over 2,000 yards, was improved by war’s end to 4,500 yards, again commonly exceeded in action. High-explosive mortar bombs weighed in at about 25 pounds (11.3 kilograms), while smoke rounds were heavier at 32 pounds (14.5 kilograms). In practice, the weapons were often called “chemical mortars” since they were only used by the CWS. On April 1, 1944, both platoons of D Company, 82nd Chemical Battalion, were relieved from operational control of the Commanding General, 37th Division, and were placed under operational control of the Commanding General, Americal Division. They moved from their positions in support of the 145th Infantry and 148th Infantry to positions in the 132nd Infantry sector near the mouth of the Torokina River. 1 section, 1st Platoon under the command of 1st Lieutenant Leon E. Rubin (April 24, 1921 – December 13, 2008), was emplaced on Big Magine Island and was joined by the other section on April 7. From its positions on Magine Island and on the mainland, D Company, commanded by Captain Charles H. Saunders (Noveember 27, 1918 – March 8, 1978) fired 2,522 rounds of High Explosive (HE) and 125 rounds of White Phosphorus (WP) during the period, including a smoke screen to cover a tank infantry attack at Mavavia, fired by 1st Platoon from Magine Island on April 8. Destroyer bombardment of the Japanese pillboxes was the preliminary to a 132nd attack designed to rid the entire area of the enemy on April 6, 1944. As the lone destroyer ceased fire and steamed away on the afternoon of April 6, a 155 millimeter (6.1-inch) howitzer of the 221st Field Artillery and an M2 4.2 inch mortar of the 82nd Chemical Mortar Battalion – the latter under lieutenant Rubin, firing from Greater Magine Island – began a ceaseless peppering of the area to keep the Japanese on edge. Based on reports received from this area – the elongated hill mass formed by Hills 165, 155, 500, and 501 – General McClure, on April 8, instructed the 132nd Infantry to clear the area of all organized Japanese resistance and to protect the area against enemy counterattacks. A strong outpost line was being established by the 1st Battalion, 25th Infantry Regiment, 93rd Infantry Division, a segregated unit. Attached to the 132nd for the operation were, in addition to the African American 1st Infantry Battalion, the 3rd Battalion, Fiji Infantry Regiment; D Battery, 82nd Chemical Mortar Battalion; and C Company, 121st Medical Battalion. The 2nd Platoon, 82nd Chemical Mortar Battalion, commanded by 1st Lieutenant Theodore H. Cotton (October 22, 1919 – December 31, 1994), was attached to 3rd Battalion, 132nd Infantry on April 13. It left its position near the Torokina River and accompanied the infantry over the East-West Trail to Hill 500. From that position, 70 rounds HE were fired on enemy installations on Hill 150. The Japanese attempted to retake Hill 500, in which I and L Companies, following a heavy artillery bombardment, thwarted the enemy’s ambitions. On April 16, patrols determined that the Japs held a long series of strong positions to the west and southwest of Hill 500. On the morning of April 17, Japanese fire increased in intensity as I Company undertook a slow advance southward and, by early afternoon, had destroyed 2 pillboxes and taken 3 machine guns in movement around the enemy’s right flank. An all-night harassing of the firmly entrenched Japanese by the 247th Field Artillery turned into a thundering preparatory concentration on the morning of April 18 as mortars of the 132nd Infantry and the 82nd Chemical Mortar Battalion – Cotton’s platoon – joined in on the booming chorus. Advancing 3rd Battalion infantrymen found that the enemy had abandoned their positions and either withdrawn to better positions on or near Hill 501 to the south or had fled across the Saua River to the east under cover of darkness. On April 22, the platoon was released from operational control, and the Commanding General of the Americal Division reverted it to battalion control. The platoon then returned to base camp. On April 15, 1st Platoon, commanded by 1st Lieutenant Rubin, moved from Magine Island to Bougainville to a position in the rear of Mavavia Village. From that position, during the period April 15-23, 1944, the 1st Platoon fired 1,223 HE and WP rounds on enemy targets in the Mavavia River Area in support of the 24th Infantry Regiment, which, along with the 93rd Infantry Division, was attached to the Americal Division. On April 26, the platoon moved by barge to a position 800 yards east of the Mavavia River. No missions were fired during the period from April 26 to May 22, and on the latter date, the platoon was relieved from operational control of the Commanding General, Americal Division, reverted to Battalion control, and returned to base camp. | |
| Image Filename | wwii1464.jpg |
| Image Size | 2.31 MB |
| Image Dimensions | 5626 x 4369 |
| Photographer | |
| Photographer Title | United States Army Signal Corps |
| Caption Author | Written or Adapted by Jason McDonald |
| Date Photographed | April 1, 1944 |
| Location | |
| City | |
| State or Province | Bougainville |
| Country | Solomons |
| Archive | National Archives and Records Administration |
| Record Number | NWDNS-111-SC-364571 |
| Status | Caption ©2026 MFA Productions LLC Please Do Not Duplicate or Distribute Without Permission; Image in the Public Domain |
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