Tank challenges, capabilities

by Michael L. Kelley
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The one-inch-thick armor on the Marine light tanks could deflect Japanese .25-caliber small-arms and light machinegun fire but was no match for Japanese 37mm anti-tank guns firing high-explosive armor-piercing shells. In addition, the Japanese infantry used a combination of handheld explosive charges, homemade gasoline bombs and anti-tank mines to destroy American tanks.

They were fearless when it came to attacking a tank. If a tank had no friendly infantry support to cover it, the Japanese would spring out of the jungle and swarm a tank, jamming the sprockets with rifle barrels and setting the tank on fire with gasoline. Sometimes a crew could escape out the hatches, but all too often, they died along with their vehicle. Many burned alive. If a crew managed to escape from a tank, the Japanese would cut them down with small-arms fire and stab them with their bayonets.

In short, tanks were dependent on infantry for protection. As tanks crawled forward, troops followed immediately behind, ready to shoot Japanese infantry that attacked the tank. They also acted as the tank’s eyes. The infantry could advise the tank crew of danger. Later in the war, communications and tactics were developed to improve the deployment of tanks and infantry operations.

Besides the Japanese, the No. 1 enemy of the tanks was the jungle. The jungle was an excellent tank killer. Tanks could bog down on muddy jungle trails, in swamps or while trying to cross streams and rivers. The jungle was a wet environment. Every few days, the skies would pour heavy rain on the jungle, making it a muddy mess for any type of vehicle, especially heavy tanks.

Tanks were severely limited in the South Pacific, but when they could be used, they were devastating. The Marine light tank (M2A4, M3 and M3A1) was one of the ugliest examples of an ugly breed of weapons. Tall for its width and boxy, it looked like it belonged in World War I, yet it was the best light tank of the war in the jungle. It was deadly when the targets were enemy bunkers or machinegun pillboxes.

Photo: The M2A4 and M3 were “one of the ugliest examples of an ugly breed of weapons,” tall and boxy.

Like all tank guns, the 37mm gun could fire armor-piercing or high-explosive ammunition. It could fire canister rounds that emitted a horde of small fragments from the barrel like a shotgun for use against enemy infantry in the open. The light tanks also carried a variety of weapons such as two .30-caliber machineguns, one in the hull and one mounted atop the turret. These tanks could run through the jungle underbrush and knock down small trees.

Crews found them to be very reliable but very cramped inside. In the jungle, the temperature inside the tank could reach more than 100 degrees. Tanks of that era were not ventilated. A crewman had to put up with infernal heat to accompany the very loud cacophony of noises a tank makes on the move. When possible, crews rode with hatches open to let air inside and get better visibility. This was risky, however, as the enemy could shoot a crewman in the head and throw a hand grenade into the open hatch, blowing up the tank.

Photo: The jungle heat combined with the tank’s interior heat caused crewmen to ride with hatches open, which was risky.

In combat, vision was a major problem. It was very difficult to see where you were going when driving through the thick jungle, as underbrush and hanging vines and trees blocked the vision ports.

The crew lived a rough and dangerous life. A hand grenade thrown inside the tank amid nearly a ton of high-octane aviation gasoline and high-explosive ammunition would turn it into a fiery tomb for the four-man crew. The crew compartment layout was a danger in itself. A long driveshaft tunnel ran down the middle of the floor, connecting the Wright Continental W-670-9A air-cooled radial aircraft engine and transmission to the drive sprockets. The gunner had to be careful not to trip over the tunnel while operating the turret and 37mm main gun.

In the early-model M2A4 tanks, there was no intercom, so the tank commander, who sat above the driver, had to signal the driver where to go by placing his foot on the driver’s shoulder and pressing down – pressing the left shoulder for a left turn and right shoulder for a right turn. Pushing down on a driver’s head was the signal to stop. In combat, when the commander was excited, his commands to the driver could be confusing, and a driver could get beat up by all the boot commands to his body. Later-model M2A4s, as well as the M3 and M3A1 models, all had an RC-61 four-station interphone for the commander to talk to his crew.

Early M2A4 tanks were equipped with a SCR-193 radio receiver. Later models had the SCR-210 radio receiver. The platoon leader’s tank was also equipped with an SCR-245 transmitter-receiver command radio. The platoon leader could talk with his command post and give instructions to his tank commanders in each tank. He could not communicate, however, with any infantry units supporting his tanks. Later in the war, the Marines equipped each tank with an external interphone on the tank’s rear so the infantry could talk with the tank commanders. On Guadalcanal, the infantry had to use hand signals or yell at the tank commander to give him directions.

The basic ammunition load for these light tanks was about 103 rounds of 37mm ammunition, 500 rounds of .45-caliber ammunition (for the crew’s .45-caliber sub-machineguns) and 8,000 rounds of .30-caliber ammunition for all the machineguns. The four-man crew consisted of a driver, seated in the left front bow, a machine gunner, seated in the right front bow, the gunner for the 37mm gun in the lower turret and the tank commander, seated in the upper turret, who also acted as a loader for the main gun. A coaxial .30-caliber M1919A4 machinegun was mounted on the right side of the 37mm main gun in the turret. An M5A1 telescope was mounted on the left side of the main gun for vision and fire control. Total vision slots for the crew were four in the hull and six in the turret cupola.

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