In Theodor Geisel's popular children's tale The Lorax, the Once-ler uses fanciful logging machines to swiftly chop down the fictional truffula trees. Dr. Seuss might as well have thought of the kind of monstrous tree crushers the US Army had used to level forests in Vietnam.
In 1968, the Army leased two of these vehicles from the LeTourneau company and quickly sent them off to Southeast Asia. After American troops began flooding into South Vietnam, the Pentagon quickly realized it was unprepared to deal with Viet Cong deception and camouflage.
"U.S. Military leaders had recognized early the tremendous advantage the jungle offered the Viet Cong and North Vietnamese Army in terms of limiting the movement … modern military equipment … and in protecting their bases, their lines of communication, and their arsenals," US Army Maj. Gen. Robert Ploger wrote in Vietnam Studies: U.S. Army Engineers, 1965-1970. "As early as November of 1965 General Westmoreland put his staff to work looking for means of jungle clearing."
At the time, Army Gen. William Westmoreland was in charge of the top American headquarters in the country, Military Assistance Command – Vietnam, or MACV. In the end, while fearsome looking, the commercial machines just weren't suited to combat.
Even before the tree crushers had arrived, MACV's land clearance project was in full swing. US Air Force planes and Army helicopters sprayed herbicides and dropped fire bombs to clear away the foliage.
On the ground, specialized engineer companies used bulldozers with huge blades called Rome Plows—the Rome Company of Rome, Georgia made the equipment—to uproot trees and other ground cover. With chainsaws, hand tools and even gas-powered lawnmowers, individual troops did their best to deny the communist guerrillas any hiding spots.
Founded in 1929, LeTourneau was already an established name in construction, logging and other heavy duty-vehicles. Despite interest from Army engineers back in the States, MACV initially balked at sending the company's Transphibian Tree Crushers into a war zone, according to Ploger.
Designed for civilian logging firms, the 60-ton vehicles had three five-bladed "wheels," two right in front of the driver's cab and one at the rear to steer. As the Tree Crusher drove forward, a large push bar would use the brute strength of the engines to knock trees over. The sharp wheels would break up the logs as the machine plodded along.
MACV was worried the weight and generally ungainly nature of the vehicles would make them ill-equipped to handle the hazards of Vietnam's jungles—especially with rebels possibly shooting at the operators. "Flotation characteristics were appealing, but it was only marginally effective in the water," Ploger noted.
Still, American commanders were eager for new, faster ways to clear away the jungle. Even the fastest herbicides took days for maximum effect—and could be washed away in heavy rains.
The 1st Logistical Command, the Army's main supply entity in South Vietnam, eventually settled on a compromise. Rather than buy any of the vehicles, the ground combat branch would simply lease two Tree Crushers from LeTourneau and test them out for almost a year.
In July 1967, the Army stood up a provisional unit to handle the vehicles, get crews up to speed on their new rides and clear the terrain around Long Binh, northeast of the capital Saigon. A little more than three months later, the Army tacked the Tree Crushers onto the 93rd Engineer Battalion at nearby Bear Cat for more far flung operations.
During the evaluation, the ungainly vehicles racked up some impressive statistics. The two Tree Crushers cleared more than 2,000 acres around Long Binh by themselves, the 93rd's engineers reported in one operational report. After joining the 93rd, LeTourneau's beasts leveled nearly another 1,200 acres in the surrounding environs.
"Trees up to three feet in diameter which ranged up to 50 feet in height … presented little obstacle to the tree crusher," the 93rd explained. "No hesitation is perceptible in the motion of the machines through tall brush, thickets and trees up to 12 inches in diameter."
Under the right conditions, a single Tree Crusher could sweep through four acres every hour— 32 in an eight hour work day. By comparison, a standard landing clearing unit with 30 Rome Plow-equipped bulldozers might clear 150 to 200 acres a day (less than seven acres per vehicle), according to Ploger.
But LeTourneau's vehicles were far from perfect for the job. The Tree Crusher's tall profile made it a perfect target for enemy troops.
If the water-cooling system got damaged, the engine would give out. Electrical components were situated in such a way that they could easily become waterlogged.
And the heavy vehicles got stuck in the swampy, jungle terrain. A lot. The unit's truck-mounted crane was poorly suited to fishing them out of the mud. The Army evaluators suggested that the heavy-duty M-88 tank recovery vehicle—a fully armored, tracked design—would work better.
Crews had no defenses during an attack either. The ground combat branch didn't even assign weapons to the unit for the first five months.
In April 1968, the engineers finally handed the two vehicles back with a list of suggested improvements, another operational review noted. The soldiers proposed a vehicle with 12-pointed, multi-section wheels that would have less trouble navigating uneven paths.
A lower profile frame would make the new Tree Crusher harder to hit. An air-cooled engine and rearranged wiring could prevent breakdowns.
Most importantly, the troops wanted an armored turret on top with a .50-caliber machine gun. Claymore mines strapped to the sides would blast a hail of steel balls to brush off guerrillas during any ambushes.
MACV and the Army weren't interested. Spraying gallons of Agent Orange and other defoliating chemicals was cheaper and easier all around. Engineers driving bulldozers continued beating back the bush on the ground.
LeTourneau continued making commercial construction and mining rigs for years afterwards. Officials in Mackenzie, British Columbia, Canada tout their G-175—now a road-side tourist attraction—as the "World's Largest Tree Crusher."
In 2011, LeTourneau's parent corporation Rowan Companies sold the firm to a Chinese buyer, Joy Global. Joy doesn't make Tree Crushers and the concept appears to have largely disappeared, as well.
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