The M3 Lee is an WWII-era U.S. medium tank. The vehicle was named after the Confederate General of the U.S. Civil War, R. Lee. Also, widely recognized under its U.K. designation, M3 Grant, named after the General of the federal troops U. Grant. M3 was created in 1940 on the basis of the M2 tank, and saw mass production from June 1941 through December 1942. A total of 6,258 M3 tanks of various modifications were produced.
After the development of the M2 medium tank, the Battle of France showed that such a tank was not going to be capable to go against the German Panzer IIIs and Panzer IVs and their Panzer Divisions. With the Western Allies now embroiled in the North African campaign against the Germans and Italians, the Allies needed a good tank capable of going against the Panzer tanks, and they needed it quickly.
The M3 Lee tank started from the basis of the M2 Medium Tank, using the chassis and the VVSS suspension system. It was to mount the 75 mm cannon, however it was discovered that the United States does not have a turret design that can mount the 75 mm gun. So as development on the turret proceeded, the 75 mm on the M3 Lee would be a sponson mounted. This design was tested on the M2 medium tank as the T5E2, which was approved for the M3 Lee design. The M3 Lee featured a medium tank with two guns, the 75 mm on the hull sponson mount, and a 37 mm with a coaxial machine gun on a turret, a cupola on the turret had its own machine gun. The use of two gun mounts on a tank was similar to the German Neubaufahrzeug and Soviet T-35 tanks. The M3 Lee's 75 mm gun however presented a huge advantage over contemporary tank armaments, the 75 mm could fire high-explosive rounds for against infantry, yet could fire a shell with a high enough velocity for anti-tank purposes.
The M3 Lee's faults was the high profile and the sponson mount for its armament. The M3 Lee was 10 ft. 3 in. tall, a feet taller than the M2 medium tank. The 75 mm on a sponson mount meant that the main armament of the tank had a limited traverse compared to a rotatable turret and forced the tank to reveal much of its body in order to aim the gun at the enemy. The M3 Lee was also constructed out of rivets (which increased spalling) and had a smooth track design which reduced ground traction. Despite these disadvantages, the Allies happily accepted them as they were critically low on tanks, and German Colonel Hans von Luck considered them superior to the Panzer IVs.
The initial batch of M3 Lees were given to the British for their campaign at North Africa. The British experience with the M3 Lee pointed out most of the M3 Lee's flaws, but they were concerned with the lack of radio in the turret and a lacking in armor, with which they modified the M3 Lee to accommodate. The new design had a new cast turret with room for a radio, the hull had thicker armor, and the turret cupola's machine gun was removed for a simple hatch. The modified M3 Lee also required one less crew member due to the radio now being in the turret for the commander rather than for a radio operator. The British ordered 1,250 of these modified M3 medium tanks.
On August 1941, production started on the M3 Lee, though the armor was thicker than initials batches of the tank due to its combat experiences. A majority of these were completed at Baldwin Locomotive Works in Philadelphia, Pennsylvania. Of the total 6,258 M3s built between start up to the end of production in December 1942, 2,855 units went to the British and 1,386 went to the Soviet Union. Other users of the M3 Lee were the Australians and Indians in the Pacific Theater. The M3 Lee arriving in British arsenal caused confusion as the same "M3" designation was given to the M3 Light Tank. This set off the tradition of naming American tanks after generals, where the M3 medium tank earned the Lee for the Americans (Grant for the British variant) and the M3 light tank earned the Stuart.
Combat experience with the M3 Lee was complicated, but favorable. In Africa, the Lees and Grants in British and American service surprised the German forces when they could withstand the 50 mm KwK 38 L/42 gun and 75 mm KwK 37 L/24 howitzer armament on the Panzer IIIs and Panzer IVs. The M3 Lee proved reliable and adequate in armor protection. The Soviet's experience with the M3 Lee was less favorable, as their T-34 tanks were much better in combat performance. The Soviets euphemistically called it a "grave for six men" and the Lee tanks were relegated to the secondary fronts or repurposed as armored personnel carriers. In the Pacific, the M3 Lees were lent to the Australians and Indians, which proved vastly superior to the Japanese tanks in service. The only American use of the M3 Lee at the Pacific Theater was during the Battle of Makin Island.
The M3 Lee served fine as a stop gap solution for the American tank development. They performed very well on the combat field and proved very reliable. However, once a 75 mm turret was finally designed, the M3 Lee was redesigned to use it, and the resulting tank was the M4 Sherman, which will go on to replace the M3 tanks in the Allies as they are withdrawn from service. Even if it wasn't, the M3 was becoming obsolete due to newer German tanks being deployed, such as the Panther, Tiger I, or improvement of of old chassis like Panzer IV Ausf. G and StuG III Ausf. F. Its obsolescence was a consequence of its own rather unique development and anachronistic design, limiting this medium tank's service life to a mere two years in Allied hands. However it lived on until the end of WW2 in some modifications such as tractor and recovery vehicle. The chassis and running gear were adapted by the Canadians to develop their Ram medium tank.