By Richard Anderson and the team.
Background
WESTERN DESERT, EGYPT. 1942-09-19. TANK CREW OF THE ROYAL SCOTS GREYS AND THEIR GENERAL GRANT M3 MEDIUM TANK. THIS TYPE OF TANK HAS BEEN ISSUED TO THIS REGIMENT ON ITS RECENT MECHANISATION. THE REGIMENT HAD PREVIOUSLY FOUGHT IN THE SYRIAN CAMPAIGN AS HORSE CAVALRY. AWM025033
George Burling Jarrett – Ordnance Hero
George Burling Jarrett was born in Haddonfield, New Jersey on October 14, 1901. He joined the Army as a Reserve officer in 1927, before the War Department called him to active duty in 1939 as a 1st Lieutenant. He served at the U.S. Army Ordnance School at Aberdeen Proving Ground with Major Robert Ickes and became curator of the Ordnance Museum. He arrived in North Africa in February 1942 with the official assignment of orienting the British to U.S. equipment, but he quickly became interested in analyzing Axis ordnance. Ordnance recognized the importance of Jarrett’s seminal intelligence work with German ordnance in North Africa with a promotion to lieutenant colonel and command of the newly created Foreign Material Branch at Aberdeen in late 1942. He later returned to the European Theater of Operations in 1945 as technical advisor to the Zornig Mission, exploiting German ordnance material at the end of the war. In November 1945, he returned to Aberdeen.
Colonel G.B. Jarrett. US Army
In 1946, he separated from active duty and accepted a position at Aberdeen as civilian curator of the Ordnance Museum and chief of the Technical Library. Colonel Jarrett remained in this position until his retirement from government service in 1966 (he retired from the Army Reserve in November 1961 as a Colonel). After his retirement, he joined the Ordnance Center of Technology Foundation, an organization previously established by persons interested in preserving the Ordnance Museum collections and constructing a new building for the Ordnance.
Colonel Jarrett died in 1974. In 1981 he was inducted in the US Army Ordnance Hall of Fame. In 2021, on the occasion of the 209th birthday of the Army Ordnance Corps, his work was further recognized when a new training and support facility at Fort Lee, Va., was named after him.
The Fuze Problem and Solution
The first problem Jarret took on when he arrived in Egypt was an issue with the American 75mm gun. The problem was the high-explosive projectiles shipped initially under Lend-Lease to the British in 1940 and 1941. They were Great War vintage production 75mm HE Mark I projectiles fitted with point-detonating fuzes M46 and M47, which were designed after the Great War to replace the original French fuzing. The reason was the French fuzes incorporated a “graze” function utilizing what was termed a “creep spring” that combined with a “superquick” or instantaneous fuze action would detonate either from the direct impact of the nose on a solid object or when the projectile changed direction from even a slight glancing blow on an object such as the ground or a tree. The extreme sensitivity of the fuzes caused numerous premature bursts, which led to the decision by American Field Artillerymen to remove the creep spring in the M46 and M47 fuze. That had little effect on high trajectory indirect fire but the British now found that when using the 75mm HE in direct fire, such as when firing it from a Grant tank at the Germans and Italians, the rounds would fail to explode if they grazed a target and would instead ricochet until a direct impact with the nose of the fuze set it off.
Jarrett recognized the cause of the problem and suggested the British should search for stockpiles of the old French fuze among Free French forces. He visited the Free French forces, discovering 90,000 of these rounds, which could be used until supplies of a new American design, the M48, which again incorporated a creep fuze, became available.
Face-hardened Armour and the 2-pdr gun
The second issue affected the anti-armour performance of the M2 gun rounds on the new M3 Grant tank. German main battle tanks initially encountered in the Western Desert were the Panzer IIIG and Panzer IVD and E, which came with relatively weak frontal armour, which was also not face-hardened. Some, but not all of the Panzer III tanks of Panzerregiment 8 were of a later variant (Panzer IIIH) with face-hardened and spaced armour. Furthermore, there is evidence that through 1941 some of the Panzer IV in North Africa received add-on armour, which was also likely face-hardened. Crucially however, in battlefield conditions it would have been impossible to tell one type from the other.
Face-hardened armor or face-hardened reinforcing plates creating spaced armour presented a problem to standard, uncapped armor-piercing projectiles, such as were in use with the British 2-pdr gun in 1941. Effective penetration of face-hardened armor required a projectile with a soft-metal piercing cap, which absorbed the shock of impact and prevented deformation or shattering of the projectile body when it struck. This requirement was not well understood, with the confusion increased because the Allied forces in 1941 encountered what appeared to be the same types of tanks (Panzer III and Panzer IV) with vastly differing armour performance. So e.g. a British anti-tank unit equipped with 2-pdr guns might one day enounter Panzerregiment 5, and easily defeat the frontal armour of the Panzer IIIs attacking it over combat distances, and the next day encounter Panzerregiment 8, and see its projectiles fail at the same distances. As these occurrences were rare, the problem was not understood at the time to CRUSADER. Furthermore, the only Panzer III tanks captured by the Allies, during the failed Easter and 1/2 May attacks on Tobruk, were Panzer IIIG variants, which would have presented no problem to the 2-pdr.
British soldiers inspecting a captured German PzKpfw III tank, 2 May 1941. IWM E2687
During CRUSADER, the Germans lost a large number of tanks, with two immediate consequences – first, captured vehicles enabled the Allies to conduct firing tests, which quickly confirmed the challenge the standard anti-tank weapons now faced, and secondly, the loss of over 90% of German tanks required a wholesale rebuilding of the force, which was done with Panzer IIIJ variants, which came with 50mm face-hardened armour from the factory. As such, in Rommel’s counteroffensive in late January 1942, Allied tank and anti-tank guns were almost helpless against these new tanks.
Battlefield remains at Sidi Rezegh, Western Desert, 1941. Springbok Record (Lt. Co. Harry Klein) via Wikipedia
The solution to this problem was to introduce armour-piercing capped (APC) projectiles. As far as the new M3 Medium tanks that started arriving in numbers in the Middle East from late 1941 was concerned however, this ammunition was not available for their main gun. Unfortunately, manufacturing the APC projectiles was a much more complex industrial process than producing the simple AP projectiles. Thus, while the US Army Ordnance Committee standardized 75mm APC M61 in the fall of 1940, production did not begin until mid-1942, too late to reach the North African theatre. Consequently, at first only 75mm AP M72 was available. As noted, when the first tests against captured German tanks were carried out near Cairo in March 1942, they found AP M72 relatively ineffective at ranges over 500 yards versus the Panzer III and Panzer IV – this was known to the Germans (see here), although they did not know whether a solution had been implemented.
This had indeed been the case. An Australian officer, Major Northy, invented an effective expedient. He mated captured German 75mm APC projectiles to American cartridge cases with enthusiastic support from an American Ordnance officer, Captain (later Major) George B. Jarrett, although there are different views of how invented this idea – see ‘Further Reading’). As a stock of about 15,000 of these rounds had been captured during CRUSADER, sufficient rounds could be made available to the ca. 3-400 Grant tanks in theatre to enable them to fight against German tanks with face-hardened armour with success.
CRUSADER had thus provided ordnance intelligence with two major findings – the discovery of face-hardened armour on German tanks and its effects, and the solution to the problem this posed.
Sources
Hunnicutt, Sherman, p. 89.
Mayo, On Beachhead and Battlefront, pp. 23-31.
R. Blake Stevens, “George Burling Jarrett (19-01-1974): The Origins of Modern U.S. Ordnance Technical Intelligence – Part II”, Small Arms Review, 2014.
U.S. Army Ordnance Corps Hall of Fame.
Ordnance dedicates training facility to Col. George B. Jarrett
See here for a discussion of the armour issue on German tanks.
How surprised were the Germans by the M3 Grant tank?
Of Interest
The Crusader Project 