It is difficult to think of a more important tank to the British and Commonwealth war effort during the early years of WWII than the American built M3, a tank which was made available to the British in large numbers and one which would make a telling contribution during the savage desert battles of the North African campaign. A tank which was something of a compromise, the Americans had seen that their existing medium tank was already outclassed by the latest German designs which were marauding through Europe and a new tank designed around a more powerful 75mm gun had to be produced. Unfortunately, no existing turret was capable of housing such a gun and it would take time to produce a new one (this new tank would be the M4 Sherman), so the M3 was an attempt to provide the best of both worlds in a timely manner.
The only way to equip a US built medium tank with a 75mm gun at that time was to fit it in the hull of the tank, much lower on the machine than the commander would think ideal in a combat situation. Existing armoured divisions were not happy about giving up their 37mm gun, which was seen as ideal when used in the infantry support role, so the designers of the M3 incorporated both in their new tank. This meant that the tank had a particularly high profile, something which would not be a problem when operating from a concealed position, but when operating in the flat, wide open deserts of North Africa, it presented a tempting target for Wehrmacht gunners.
Supplied in two basic variants, the British version featured a modified turret with a clearly discernible bulge at the back of the turret which was needed to house the radio equipment and the American version, which did not feature the turret bulge and had the radio equipment installed inside the hull. With two guns to fire during combat, the hull of an M3 could be a busy place, with six men in British tanks (which were known as M3 Grant tanks) and seven in the US M3 Lee tanks (the extra man was needed to operate the radio equipment).