In June 1940 the US army issued a specification calling for a 1/4–ton combat truck with all-wheel drive to carry a 600lb payload and weigh no more than 1,300 lbs. From the 135 manufacturers who were invited to compete and to provide specimens within 75 days, only two companies took up the challenge, American Bantam of Butler, Pa., and Willys-Overland of Toledo, Ohio. Only Bantam managed to produce a vehicle within the time limit and to the army’s specifications, and as a result that company would receive the initial contract. Trials soon revealed that the Bantam vehicle, as good as it was, to be considerably underpowered and insufficiently robust. Willy-Overland’s chief engineer however considered the army specification to be far too stringent and refused to compromise. Instead he set about developing his idea of what the army should have, a stronger vehicle with a more powerful engine (a 2,199cc Willys MB 4 cylinder petrol engine developing 60bhp at 4,000 rpm). The resultant vehicle weighed in much heavier than the original army specification (2,453 lb) but this allowed it to carry a greater payload (800 lbs or 1,000lbs towed) at a maximum speed of 65 mph for a range of 300 miles. After much argument and testing, the Willys Combat car was finally accepted by the army and a legend was born. Meanwhile the Ford motor company of Detroit Michigan had belatedly become interested in the specification and had put together their own vehicle, known as the GP (for General Purpose), but since its engine was less powerful the army decided to standardize on the Willys design and have it built by both firms simultaneously (when built by Ford it was designated the Model GPW). Produced by the tens of thousands, the Jeep, as it was affectionately known, was used by every allied army and proved so popular and useful that supply could never keep up with demand.. The Jeep remained in service unchanged until 1955, after which it was replaced by improved models.