Editing M3 Lee (section)

==Development==
The U.S. funded tank development poorly during the interwar years, and had little experience in design as well as poor doctrine to guide design efforts. Only a few tanks were built (35 between 1920-1935). A new medium tank was designed in 1938, tested as the T5 and accepted as the [[M2 medium tank|M2 Medium]]. The M2 used a radial engine and vertical volute suspension among many of the features of the [[M2 light tank]]. 

In {{year|1939}}, the [[United States Army|U.S. Army]] possessed approximately 400 tanks, mostly [[M2 Light Tank]]s, with 18 of the M2 Mediums as the only ones considered "modern."<ref>Hunnicutt 1978 p. 44</ref>

[[File:M3 tank riveting LOC fsa 8e10699.jpg|thumb|left|The armor plate on the M3 was too heavy for welding and had to be riveted in position.]]

The M2 Medium Tank was typical of [[armored fighting vehicle]]s (AFVs) many nations produced in 1939. By the time, the U.S. entered the war in 1941, the M2 design was already obsolete with a [[37 mm Gun M3|37 mm gun]], an impractical number of secondary machine guns, a very high silhouette, and {{convert|32|mm|in|abbr=on}} frontal armor. 

At the end June 1940 the National Munitions Program was introduced to address the United States lack of readiness in case of war across all branches of the armed forces. The program specified the building of over 1,700 medium tanks by the end of 1941.<ref>Chamberlain & Ellis p7</ref> In mid July, [[Armor Branch|Armored Force]] under Brigadier General [[Adna R. Chaffee Jr.]] was formed to take over responsibility for tanks which had previously been split between the Infantry and Cavalry commands. Work was begun with industry to create the production facilities leading to a contract in August for [[Chrysler]] to build the [[Detroit Arsenal (Warren, Michigan)|Detroit Tank Arsenal]] which was expected to turn out 10 Medium M2A1 (an improved M2 Medium) per day.<ref>Chamberlain & Ellis p9-10</ref>

However, the US Army's assessment of the German [[Panzer III]] and [[Panzer IV]] medium tanks' success in the [[Battle of France|French campaign]] was that a 75mm gun was a necessity.{{Efn|The Panzer IV was the only German tank with a 75mm gun, which was a short barrelled weapon- the [[7.5 cm KwK 37]] for infantry support use.}} The M2A1 could not be fitted with a 75mm weapon in its turret. Producing a new turret design would delay production and while it was decided to start work on a 75mm turret design, an interim solution was sought. An experimental modification of an improved M2 Medium into a [[Self-propelled artillery|self-propelled gun]] - the T5E2 - had been tested with a 75m pack howitzer in the front hull and it was decided to base the interim design on this work. The existing M2 hull could be used with a redesigned superstructure and the M2A1 37&nbsp;mm turret{{Efn|The 37&nbsp;mm turret mounted on the M3 design replaced the rangefinder turret of the T5E2 design.<ref>Chamberlain & Ellis p11</ref>}}. The contract for 1,000 M2A1s was cancelled and replaced with one for 1,000 M3s, though the M3 had not yet been designed. The Ordnance Department allocated 60 days for the design work.<ref>Chamberlain & Ellis p11</ref> At the same time, the 75 mm gun design was started by [[Watervliet Arsenal]]; the new gun was based on the [[Canon de 75 modèle 1897|75mm field gun]].<ref>Chamberlain & Ellis p14</ref>

The design was unusual because the main weapon – a larger caliber, medium-velocity 75&nbsp;mm gun – was in an offset [[sponson]] mounted in the hull with limited traverse. The sponson mount was necessary because, at the time, American tank plants did not have the design experience necessary to make a gun turret capable of holding a 75&nbsp;mm weapon. A small turret with a lighter, high-velocity 37&nbsp;mm gun sat on top of the tall hull. A small cupola on top of the turret held a [[machine gun]]. The use of two main guns was a feature of the French [[Char B1]]{{efn|The Char B1 was designed as a self-propelled gun for use against fortifications and a turret was added to give anti-tank capability}} and the Mark I version of the British [[Churchill tank]].{{efn|The first Churchills had a howitzer to fire smoke shells in the hull}} In the French tank, it had been designed as a self-propelled gun to attack fortifications and an anti-tank capability had been added through a second gun in a small turret; the Churchill carried a gun in the front hull to fire chiefly smoke shells. The M3 differed slightly from this pattern, having a dual-purpose main gun that could fire an armor-piercing projectile at a velocity high enough for effectively piercing armor, as well as deliver a high-explosive shell that was large enough to be effective. Using a hull-mounted gun, the M3 design could be produced faster than a tank with the same gun in a turret. It was understood that the M3 design was flawed, but Britain<ref>Zaloga, ''Armored Thunderbolt'', p. 21</ref> urgently needed tanks. A drawback of the sponson mount was that the M3 could not take a [[hull-down]] position and use its 75&nbsp;mm gun at the same time.

The M3 was tall and roomy: the power transmission ran through the crew compartment under the turret basket to the gearbox driving the front sprockets. It was originally developed at the Rock Island Arsenal for T5 Phase III in 1938<ref>{{Cite web |title=Medium Tank M2: Last Place in the Arms Race |url=https://www.tankarchives.ca/2017/04/medium-tank-m2-last-place-in-arms-race.html |access-date=2024-12-22}}</ref> but in 1940 [[Spicer Manufacturing Company]] was contracted to refine the design before serial production.<ref name=":1">{{Cite journal |last=Dana |first=Charles A. |author-link=Charles A. Dana (philanthropist) |date=1955 |title=Industry and Defense |url=https://www.jstor.org/stable/45363774 |journal=Ordnance |volume=39 |issue=208 |pages=565–568 |jstor=45363774 |issn=0030-4557}}</ref> Since Spicer itself was busy producing transmissions for the light tanks,<ref name=":1" /> [[Mack Trucks|Mack Manufacturing]] from 1940, and Iowa Transmission Co. (a [[John Deere|Deere]] subsidiary in [[Waterloo, Iowa|Waterloo]]) from 1941 were tasked with manufacturing it.<ref>{{Cite web |title=British M3, M3A2, M3A3 and M3A5 Grants |url=http://the.shadock.free.fr/sherman_minutia/manufacturer/m3grant/m3grant.html |access-date=2024-12-22 |website=the.shadock.free.fr}}</ref> Steering was by differential braking, with a turning circle of {{convert|37|ft|m|abbr=on}}. After some experiments with hydraulically powered steering on the earliest M3s mechanical long-lever operation was adopted for production.<ref>{{Cite web |date=2015-12-28 |title=#36 The Transmission, Differential, and Final Drives: Called the 'Powertrain' and It Was Great On The Sherman! {{!}} The Sherman Tank Site |url=https://www.theshermantank.com/sherman/the-transmission-differential-and-final-drives-called-the-powertrain-and-it-was-great-on-the-sherman/ |access-date=2024-12-22 |language=en}}</ref>

The [[vertical volute spring suspension]] (VVSS) units possessed a return roller mounted directly atop the main housing of each of the six suspension units (three per side), designed as self-contained and readily replaced modular units bolted to the hull sides. The turret was power-traversed by an electro-hydraulic system in the form of an electric motor providing the pressure for the hydraulic motor. This fully rotated the turret in 15 seconds. Control was from a spade grip on the gun. The same motor provided pressure for the gun stabilizing system.

[[File:M3-lee-camp-polk.jpg|thumb|left|Crew exiting a "disabled" M3 tank during training maneuvers held at [[Fort Johnson|Camp Polk]] in February 1943]]
The 75&nbsp;mm gun was operated by a gunner and a loader; sighting the gun used an M1 periscope – with an integral telescope – on the top of the sponson. The periscope rotated with the gun. The sight was marked from zero to {{convert|3000|yd|m|abbr=on}},{{efn|later 3,500 yards}} with vertical markings to aid deflection shooting at a moving target. The gunner laid the gun on target through geared handwheels for traverse (15° to left and to right) and elevation ( +20° to -9°).<ref>Rottman 2008, p. 32</ref> The shorter barreled 75&nbsp;mm M2 cannon sometimes had a counterweight added at the end of the barrel to balance the gun for operation with the gyrostabilizer until the longer 75&nbsp;mm M3 variant was brought into use.<ref>[http://afvdb.50megs.com/usa/m3lee.html "Medium Tank M3 Lee"]</ref>

The 37&nbsp;mm gun was aimed through the M2 periscope, mounted in the mantlet to the side of the gun. It also sighted the coaxial machine gun. Two range scales were provided: 0–{{convert|1500|yd|m|abbr=on}} for the 37&nbsp;mm and 0–{{convert|1000|yd|m|abbr=on}} for the machine gun. 

[[File:M-3Grants-E 014053.2.jpg|thumb|British Grant (left) and Lee (right) at [[El Alamein]] (in the Egyptian [[Western Desert (Egypt)|Western Desert]]) 1942, showing differences between the British turret and the original design of the M3]]
There were also two .30-06 (7.62&nbsp;mm caliber) [[M1919 Browning machine gun|Browning M1919A4 machine guns]] mounted in the hull, fixed in traverse but adjustable in elevation, which were controlled by the driver. These were, due to coordination issues, removed, though they would be seen on early Sherman tanks.<ref name="Chieftain/Nicholas Moran Grant Outside">{{cite AV media |first=Nicholas |last= Moran |url=https://www.youtube.com/watch?v=_p7eJr0grTc |title=Inside the Chieftain's Hatch: M3 Grant. Part 1 |publisher=World of Tanks North America |website=youtube}}</ref>{{Efn|Two of the seven machine guns on the M2 Medium had also been in the forward hull under the drivers control.}}

Though not at war, the U.S. was willing to produce, sell and ship munitions including armored vehicles to Britain. The British had requested that their [[Matilda II]] [[infantry tank]] and [[Crusader tank|Crusader]] [[cruiser tank]] designs be made by American factories, but this request was refused. With much of their equipment [[Dunkirk evacuation|left in France after the British Army was evacuated from Dunkirk]], the equipment needs of the British were acute. Though not entirely satisfied with the design, they ordered the M3 in large numbers. British experts had viewed the mock-up in 1940 and identified features that they considered flaws – the high profile, the hull mounted main gun, the radio position in the hull rather than in the turret, the riveted armor plating (whose rivets tended [[Spall|to pop off inside the interior in a deadly ricochet]] when the tank was hit even by non-penetrating rounds), the smooth track design, insufficient armor and lack of splash-proofing of the joints.{{sfn|Fletcher, Great Tank Scandal|page= 90}}

The British desired modifications for the tank they were purchasing. A [[bustle rack]] was to be made at the back of the turret to house the [[Wireless Set No. 19]]. The turret was to be given thicker armor than in the original U.S. design, and the machine gun cupola was to be replaced with a simple hatch. Extended space within the turret{{Efn|Designed by L.E. Carr of the British Department of Mechanization and tested on a M2A1 Medium<ref name=TankArchives>{{Cite web |title=Lee and Grant: American Generals in British Service |url=https://www.tankarchives.ca/2018/05/lee-and-grant-american-generals-in.html |access-date=2023-10-28 |website=Tank Archives}}</ref>}} of the new M3 also allowed the use of a smoke bomb launcher{{Efn|The "2-inch Mortar Mk III (smoke)"}}, although the addition of the radio would take the space for storage of fifty 37&nbsp;mm rounds, reducing the ammunition capacity for that gun to 128 rounds. Several of these new "Grant" tanks would also be equipped with sand shields for action in North Africa, though they often fell off.<ref name="Chieftain/Nicholas Moran Grant Outside"/><ref name="Chieftain/Nicholas Moran Grant Inside">{{cite AV media |first=Nicholas |last= Moran |url=https://www.youtube.com/watch?v=Pu8NwLls7PY&t=1048s |title=Inside the Chieftain's Hatch: M3 Grant. Part 2 |publisher=World of Tanks North America |website=youtube}}</ref> With these modifications accepted, the British ordered 2,000 Grants, with 1,685 ultimately built.

Contracts were arranged with four US companies for 500 tanks each: [[Baldwin Locomotive Works|Baldwin Locomotive Company]], [[Pullman Company|Pullman Standard Car Company]], [[Pressed Steel Car Company]] and [[Lima Locomotive Works|Lima Locomotive Company]]. The total cost of the orders was approximately US$240 million ($120,000 per piece), including funds for factory re-tooling. That was the total of all UK government funds held in the US; it took the [[Lend-Lease|US Lend-Lease act]] to solve the financial shortfall and fund future equipment orders (for comparison, Lend-Lease cost of a M3 was $64,814).<ref name="costs" />  The order with Baldwin was later increased from 500 to 685. Lima did not produce a single Grant against its contract as it took the company so long to complete the steam locomotives already in production to create factory space and to tool-up that M3 production was winding down before it was ready. It was therefore agreed that Lima would supply 500 of the new M4 Sherman instead. Lima actually undertook the T6/M4 development while it was unable to manufacture the Grant and, as the other companies were all too busy, was the first company to begin producing the M4 in March 1942 with the M4A1 variant. The first 28 M4A1s built were British contract tanks as Grant replacements but the remainder of the order was subsumed into Lend-Lease.

The prototype M3 was completed in March 1941 and production models followed, with the first British-specification tanks produced in July. Both U.S. and British tanks had thicker armor than first planned.{{sfn|Fletcher, Great Tank Scandal|page= 93}} The British design required one fewer crew member than the US version due to the radio in the turret. The U.S. eventually eliminated the full-time radio operator, assigning the task to the driver. After extensive losses in Africa and [[German invasion of Greece|Greece]], the British realized that to meet their needs for tanks, they would have to take both the Lee and the Grant types.

The U.S. military used the "M" (Model) letter to designate nearly all of its equipment. When the British Army received its new M3 medium tanks from the US, confusion immediately set in<ref>Zaloga (Armored Thunderbolt) p. 18</ref> between the different M3 medium tank and M3 light tank. The British Army was in the process of using names for its own tanks instead of designations and named its American tanks after American military figures,<ref name=TankArchives/> although the U.S. Army never used those terms until after the war.<ref name="stout1946_136">{{Cite book |url=https://archive.org/details/tanmightyfi00stou |title=Tanks are Mighty Fine Things |last=Stout |first=Wesley W. |publisher=Chrysler Corporation |year=1946 |page=[https://archive.org/details/tanmightyfi00stou/page/n149 136] |access-date=2019-07-11}}</ref><ref>Zaloga (Armored Thunderbolt) p. 19</ref> M3 tanks with the cast turret and radio setup received the name "General Grant", while the original M3s were called "General Lee", or more usually just "Grant" and "Lee".<ref name="stout1946_136"/><ref>Bishop ''The Encyclopedia of Weapons of World War II'' p. 34</ref>

The chassis and running gear of the M3 design was adapted by the Canadians for their [[Ram tank]]. The hull of the M3 was also used for self-propelled [[artillery]] as with the original design of the [[M7 Priest]], of which nearly 3,500 were built, and recovery vehicles.