‘America’s greatest contribution to modern warfare,’ was US General George C. Marshall’s appraisal of the Willys Jeep. It appeared on the front-line of almost every World War Two theatre as a reconnoissance vehicle, machine-gun mount, ammo carrier, wire layer, taxi, pickup truck, stretcher-bearer and go-between. It whisked the wounded away from the Nazi spearhead in the Battle of the Bulge, hauled canons across the snowfields of Iceland, helped to blow up Rommel’s fuel tankers in Egypt and served with US marines in the western Pacific.

When America made the decision to enter World War Two, the US Army needed to rapidly expand its fleet of military vehicles. A new light vehicle built to a standardised specification was essential. The US Army summarised its requirements in July 1940 and sent them to 135 American automotive manufacturers. It demanded four driven wheels, 85lb ft of torque, space for three people, a rectangular body of 80in in length, operating speeds of 3 to 50mph, a payload of 300kg and an unladen of less than 590kg. The need was urgent. Manufacturers were asked to submit their prototypes within 49 days and provide a fleet of 70 test vehicles within 75 days.

Willys-Overland Motors and American Bantam Car Company entered the competition to meet the US Army’s demands. The Ford Motor Company joined them shortly afterwards. American Bantam won the bid, as it was the only company that committed to meeting the tight deadlines. Karl Probst led the design process of the first prototype, which was delivered to the US Army test centre on September 23.

Unfortunately, Bantam lacked the manufacturing capacity to produce the new vehicles in sufficient quantities. The US Army asked Ford and Willys to complete their prototypes and provided the Bantam blueprints as assistance. Both submitted prototypes – which turned out to be very much alike – by November. An order of 1500 field-testing units was placed with each company. By this stage, the original 590kg weight limit was accepted to be unrealistic and increased to 980kg.

Bantam’s vehicle was named the BRC 40 and production started at the end of March 1941. It could not build the required 75 vehicles per day, so contracts were also given to Ford and Willys. In July 1941, the War Department made the decision to select a single provider for the next order of 16,000 vehicles. Willys won the contract, largely thanks to its powerful ‘Go Devil’ engine.

The four-cylinder sidevalve engine was developed from an earlier design by Willys’ chief problem-solver, Delmar Roos. He took a standard engine and ran it at full throttle on a test rig. The cast-iron pistons melted after 22 minutes. He replaced these with tin-plated aluminium items, redesigned the cooling system and repeated the test. The valves burned out after 50 hours. He redesigned the valve seats. The result: an engine that would run at maximum revs for 100 hours. It also delivered significantly more torque than the US Army had specified.

By October, it had become obvious that Willys was not able to meet demand on its own. Ford therefore began producing vehicles to the Willys design. It was named the Willys MB and the Ford GPW. It was nicknamed ‘Jeep’ by army mechanics and soldiers.

Willys produced 363,000 Jeeps from 1941 to 1945. Ford made 280,000. Around 51,000 were exported to the USSR under the Lend-Lease programme.

Willys went on to produce a civilian version – the CJ – after the war. It set the blueprint for future four-wheel drive civilian vehicles such as the 1948 Land Rover. Military Willys Jeeps were produced under licence across the globe, notably by Hotchkiss in France, which built a large number of M201 models for the French Army. Jeeps played a significant role in the Korea and Vietnam wars.

The Willys Jeep is one of the most potent symbols of World War Two. It was the main vehicle supplied through the Lend-Lease programme to Great Britain, the USSR, the Republic of China and other Allied countries. It changed the course of the war and had a significant effect on the future of the automotive industry.

Willys MB Specification
Engine: 2199cc/4-cyl/sidevalve
Gearbox: 4-speed manual
Power: 54bhp@4000rpm
Torque: 95lb ft@2000rpm
0-60mph: 30+ sec
Top speed: 62mph