The fighting in the Pacific in early 1944 convinced senior Army and Marine officers of the urgent need for flamethrower tanks to deal with the threat posed by Japanese bunkers. The technical problems with the M1 portable flamethrower led to the improved M1A1, which entered production in December 1942. Although some footholds were gained, the reinforced Japanese defenses prevented any deep penetration toward Mavavia. U.S. portable flamethrowers were first used in combat during the Guadalcanal campaign in January 1943. Numerous reporters and photographers were also present. The first recorded use came three months later when U.S. Army units replaced the Marines during the expansion of the Bougainville bridgehead in late January 1943.

These early flamethrowers continued to be used in combat in the Solomons, as well as elsewhere in the Southwest Pacific Area (SWPA) such as Buna on the island of New Guinea and on the island of New Georgia. In August 1943, the U.S. Army XIV Corps began experiments to adapt the M1A1 flamethrower to the bow machine gun mount in the M3A1 light tank. As a result, the U.S. Army’s Americal Division was alerted on November 25, 1943, and began replacing the Marine regiments in mid-December 1943. Equipping the Marines with Flamethrower Tanks. Following the U.S. landings on Bougainville, the Japanese forces had built up a series of defense lines along the perimeter of the beachhead anchored by reinforced log bunkers and entrenchments. This version had several upgrades and could use thickened fuel to provide better range. Official U.S. Army accounts of flamethrower development do not identify the inventor of the idea, but some memoirs suggest that it was the brainchild of Lt. Col. Joseph Hart, who commanded the 754th Tank Battalion at the time. The M1 weighed over 60 pounds loaded and so was very difficult to carry in jungle conditions. The 3rd Marine Tank Battalion was deployed during the first phase of the Bougainville fighting, but there is no evidence that the tank flamethrowers were used at this time. The fighting on New Georgia in July 1943 against tenacious Japanese bunker defenses invigorated the effort to develop a more satisfactory mounting. The operational objective of the XIV Corps at the time was to push out the beachhead area to permit the unfettered operation of coastal airfields that were being used to harass the Japanese stronghold of Rabaul on the island of New Britain. The production of the M1 portable flamethrower began shortly before the outbreak of war in late 1941. When first deployed on Bougainville, Lehtonen’s detachment was assigned to the XIV Corps reserve. Forward detachments of the battalion deployed to Guadalcanal in May and August 1943 under the XIV Corps but were not committed to combat. Not only was the operator burdened with a heavy and bulky weapon, but it was impossible to hide once the flamethrower was ignited. It quickly became apparent that the exposed flamethrower operator was vulnerable to Japanese small arms fire. In practice, firing the flame gun through the pistol port proved difficult because of the cramped conditions inside the light tank. At that time these islands were part of the Australian-administered Territory of New Guinea. The initial combat use of the M1 flamethrower proved frustrating because of technical problems with the devices and the lack of established technical and tactical training. The idea of mounting the portable flame-thrower in a tank occurred in the late summer of 1943 on New Caledonia, where some of the CWS personnel were training flamethrower troops.
The most systematic work on tank flamethrowers took place near Noumea on New Caledonia, where the I Marine Amphibious Corps was based. As a result, Hodge was determined to use tank support to assist in clearing the bunkers. The division’s 132nd Infantry Regiment was on the far right flank facing the Torokina River. Two five-gallon fuel unit assemblies from the M1A1 portable flamethrower were used, one on the floor in front of the bow gunner’s seat and one behind the seat where .30-caliber machine-gun ammunition was normally carried. This sector was defended by the Japanese 4th South Seas Garrison, a regimental-sized force that included three infantry battalions. A system was devised to shorten the M1A1 flame gun to make it more suitable for mounting in the .30-caliber ball mount in the M3A1. Some of the M3A1 light tanks were fitted with the improvised tank flamethrowers on New Caledonia before departing for Bougainville.

The continuing buildup of Japanese forces along the beachhead perimeter in January 1944 convinced Maj. Gen. John Hodge, the Americal Division commander, to clear out the Hornet’s Nest to prevent the Japanese from pushing along the shoreline toward the heart of the American beachhead at Empress Augusta Bay. The use of the portable flamethrower from the tank seemed like a good idea since it would enable the operator to get within effective range of Japanese bunkers while being far less vulnerable to Japanese small arms fire. In spite of the modifications, it still suffered from reliability problems, especially with the ignition system in humid conditions. The 2/132nd Infantry began moving toward this defense perimeter in mid-January 1944 and set up defensive positions along the jungle fringe. In one attack, a team of engineers supporting the 8th Marines, 2nd Marine Division carefully crawled to within 25 yards of a bunker defense line and burned out three bunkers during a day’s fighting. The 2/132nd Infantry conducted attacks on January 20 and 25, 1944, in an attempt to expand the lodgment on the east side of the Torokina River. The M1 flamethrower was used successfully in combat for the first time during the fighting on Guadalcanal on January 15, 1943. © Copyright 2020 Center for the National Interest All Rights Reserved. It was originally configured as a light tank battalion, equipped with M3 light tanks and later with the improved M3A1. The battalion began to reorganize in November 1943, switching from a light tank configuration to a mixture of three medium tank companies and one light tank company. These improvised tank flamethrowers were mounted in light tanks of both the 3rd Marine Tank Battalion and the Army’s 754th Tank Battalion. The Bougainville Campaign 1944-1945 An account of the Militia at war By Anthony Staunton The largest of the Solomon Islands is Bougainville.
An officer in the 754th Tank Battalion had the idea of firing the flamethrower out of the small pistol ports on the turret of the M3A1 Stuart light tank. It took some time for the equipment to arrive, so the two tank companies of the forward detachment sent to Bougainville were still equipped with light tanks. The 754th Tank Battalion (Light) had departed the port of New York in January 1942 and arrived on New Caledonia on March 12, 1942, one of the first U.S. Army tank battalions sent to the South Pacific after the outbreak of the war. In October 1943, a demonstration was held near Noumea to acquaint Marine and Army officers, as well as Australians and New Zealanders, with the new weapon. With the arrival of the new flamethrowers came training teams from the Chemical Warfare Service (CWS) to help instruct the troops in how to maintain and operate the devices. Invariably, the use of flamethrowers would provoke a hailstorm of small arms and mortar fire from the Japanese defenders. Introduction to the Invasion of Bougainville Island After New Georgia, the next major operation was an invasion of the island of Bougainville, which was approached by landings at Mono and Stirling in the Treasury Islands on October 25-27, 1943. The initial landings on Bougainville in November 1943 had been conducted by the 3rd Marine Division, but Vice Admiral William “Bull” Halsey wanted the division for the forthcoming New Ireland landings. Periodic patrols east of these positions disclosed an extensive set of Japanese bunker defenses that were dubbed the “Hornet’s Nest” by the Americal troops. This early design proved to be an extremely troublesome weapon, suffering from erratic ignition, short battery life, and poor durability in damp conditions. The first M1A1 flamethrowers reached the South Pacific in August 1943. Portable flamethrowers had proved useful in the initial attacks but were too vulnerable to Japanese small arms fire. The attack on the Hornet’s Nest was planned by the staff of the 2/132nd Infantry, but General Hodge moved the 1/132nd Infantry forward to conduct the attack.