17pdr SP Achilles
Encyclopedia
The 17 pounder, Self Propelled, Achilles was a British variant of the American M10 Tank destroyer
armed with the powerful British Ordnance QF 17 pounder
anti-tank gun in place of the standard 3" (76.2 mm) Gun M7. With a total of 1,100 M10s converted, the 17 pdr SP Achilles was the second most numerous armoured fighting vehicle to see service armed with the 17 pounder gun, behind the Sherman Firefly
.
The name "Achilles" was officially a designation applied to both the 3" gun and 17 pounder versions (as Achilles I/II and Achilles Ic/IIc respectively) but was little used during the Second World War
; at the time, the vehicle was called 17pdr M10, or 17pdr SP M10, or even occasionally, "Firefly". It has since become identified almost exclusively with the 17 pounder version.
carrying high velocity anti-tank guns as the best way to deal with the fast moving armour spearheads of the German Blitzkrieg
. The M10 was based on the chassis of the M4 Sherman
but carried thinner although more sloped armour
in order to comply with the high speed requirement for the tank. At the same time, the British had been examining the possibility of designing a low-silhouette self-propelled tank destroyer, preferably with a 360-degree traversing turret, with armour that would be able to resist the German 50 mm at 800 yards and mounting the 17 pounder. However with the arrival of the M10 on the battlefield in late 1942, British plans for a turreted self-propelled gun were cancelled.
The M10 was first made available to the British in 1943. These vehicles were open topped and mounted a 3" American gun, which was significantly more powerful than the Ordnance QF 6 pounder
that was mounted on British tanks of the period and was of equal power to the 7.5 cm KwK 40
used by the Panzer IV
and Sturmgeschütz III
. When introduced into service in late 1942, the thin but sloped armour of the M10 provided good protection against the standard 50 mm gun
mounted on most German tanks and anti-tank guns, and the 3 inches (76.2 mm) gun was able to easily defeat all German armour except for the handful of Tigers
deployed against the Western Allies.
The 17 pdr SP Achilles was basically a modified M10, the main difference being the gun. The main armament of the Achilles was the Ordnance QF 17 pounder
, a gun with greatly superior anti-tank performance over the standard American 3" anti-tank gun.
The 17 pounder mounted on the Achilles was able to penetrate some 140 mm of armour at 500 m (546.8 yd) and 131 mm at 1000 m (1,093.6 yd) using standard Armour Piercing, Capped, Ballistic Capped
(APCBC) ammunition impacting at a 30 degree angle. When supplied, Armour-piercing discarding sabot
(APDS) ammunition could penetrate some 209 mm (8 inches) of armour at 500 metres and 192 mm at 1,000 metres at a 30 degree angle. In comparison the 3 inches (76.2 mm) gun on the standard M10 using the same type of ammunition (APCBC) would penetrate 98 mm of armour at 500 m at a 30 degree angle, and 88 mm of armor at 1,000 meters at a 30 degree angle. Only with High Velocity Armour Piercing (HVAP) ammunition did the 3 inches (76.2 mm) gun compare with the 17 pounder, the ammunition being able to penetrate 140 mm at 500 m at a 30 degree angle, and 127 mm at 1,000 m at a 30 degree angle. However HVAP ammunition was in very short supply and it only just compared with the standard 17 pounder ammunition that was available in huge amounts for the British.
The 17 pounder required a counterweight fitted behind the muzzle brake
on its long barrel. This gave the Achilles a distinctive appearance compared to the M10 and there were attempts to disguise this by painting the brake and counterweight.
The only other change carried out on the Achilles was the addition of 17 mm (0.669291338582677 in) thick armour plates welded to the front and sides of the M10 to increase armour protection, as well as a 20 mm thick shield fitted to the top of the turret to provide protection from overhead threats that resulted from the M10 having an open top turret.
The desire to mount the 17 pounder on the M10 was governed by the degree of difficulty involved in mounting the 17 pounder on the tank itself. Luckily for the British, the initial batches of M10s had an easily modified gun mounting to facilitate the future replacement of the older 3 inch M7 gun with the newer 76 mm gun M1
. This gun mounting design allowed for the British to replace the 3 inch gun with the 17 pounder gun. The British took delivery of some 845 vehicles in 1943, but of the second version of the M10, only the T71 mark could carry the 17 pounder, the T70 mark being designed to only allow the lighter American 76.2mm M1 gun.
The British had planned to convert some 1,000 M10s into 17pdr armed variants for Normandy, but for some reason conversions were not started until April 1944. By D-Day only some 124 M10s had been converted, however the number of conversions post D-day increased and by the end of the year 816 M10s had been converted, 152 vehicles in November alone. However the low numbers at D-day meant that many British units went ashore fielding standard M10s rather than 17 pounder armed Achilles, and losses in Achilles units could at times be hard to replace, the crews receiving regular 3" armed M10s as replacements for their lost 17 pdr Achilles much to their dismay.
As a self-propelled anti-tank gun, Achilles as well as standard M10s were distributed to and operated by the regiments of the Royal Artillery
. Around 1,650 M10 tank destroyers were received by the British during the war, of these 1,100 were converted to the 17 pdr by the end of the war.
Unlike the Americans, who saw the M10 as a tank hunter, the British viewed the Achilles as a mobile anti-tank gun. The standard anti-tank gun used in infantry units in the British Army was the 6 pounder anti-tank gun, a small, light gun able to defeat the more common German Panzer IV
and Sturmgeschütz
with regular ammunition but not the heavier Tigers and Panthers
. The next generation British gun, the 17 pounder anti-tank gun, was able to deal with Tigers and Panthers but was a heavy and unwieldy weapon that could take over 12 hours to move into position, dig in and camouflage. The British knew from experience that the Germans would quickly counterattack and it took too long to set up the 17 pounders before the German heavy tanks could overrun the infantry's position.
As a result, the British used the Achilles as a quickly deployable anti-tank gun, able to reinforce a position taken by infantry and engage counter-attacking German forces while the slower towed 17 pounders were pulled up and dug in for a more long-term defensive presence. This had the advantage of mitigating the weak armour protection of the Achilles as being used defensively usually allowed it to fire the vital first shot. Usually, the only time the British used the M10 and Achilles offensively was in support of Churchill tank
units as they did not have associated 17 pdr armed tanks like Sherman
and Cromwell tank
troops did.
Achilles went ashore on D-Day, equipping units of the Royal Artillery
and Royal Canadian Artillery
in Armoured Division or Corps Anti-tank Regiments. A typical A/Tk Regiment would have 4 Batteries, 2 x Towed 17 Pdr Batteries, 1 x Achilles and 1 x M10 Battery. The M10 Battery was replaced by a second Achilles Battery as more vehicles became available. Perhaps the most successful action of the Achilles was conducted by B troop, 245th Battery, 62nd Anti-Tank Regiment, Royal Artillery attached to the Hamilton Light Infantry
during Operation Charnwood
. South of Buron, a counterattack by a mixed force of Panzer IV
and Panther tank
s of the 12th SS Panzer Regiment was defeated by Achilles and 17-pounder anti tank guns
of 245th Battery, 62nd Antitank Regiment. Thirteen German tanks were destroyed in one of the most successful antitank engagements of the campaign, for the loss of four tank destroyers and a further four damaged.
Tank destroyer
A tank destroyer is a type of armored fighting vehicle armed with a gun or missile launcher, and is designed specifically to engage enemy armored vehicles...
armed with the powerful British Ordnance QF 17 pounder
Ordnance QF 17 pounder
The Ordnance Quick-Firing 17 pounder was a 76.2 mm gun developed by the United Kingdom during World War II. It was used as an anti-tank gun on its own carriage, as well as equipping a number of British tanks. It was the most effective Allied anti-tank gun of the war...
anti-tank gun in place of the standard 3" (76.2 mm) Gun M7. With a total of 1,100 M10s converted, the 17 pdr SP Achilles was the second most numerous armoured fighting vehicle to see service armed with the 17 pounder gun, behind the Sherman Firefly
Sherman Firefly
The Sherman Firefly was a World War II British variant of the American Sherman tank, fitted with the powerful British 17 pounder anti-tank gun as its main weapon...
.
The name "Achilles" was officially a designation applied to both the 3" gun and 17 pounder versions (as Achilles I/II and Achilles Ic/IIc respectively) but was little used during the Second World War
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
; at the time, the vehicle was called 17pdr M10, or 17pdr SP M10, or even occasionally, "Firefly". It has since become identified almost exclusively with the 17 pounder version.
Origins
In the wake of Germany's successful 1939–41 campaigns, US armour doctrine had incorporated the idea of fast, lightly armoured vehiclesVehicle armour
Military vehicles are commonly armoured to withstand the impact of shrapnel, bullets, missiles, or shells, protecting the personnel inside from enemy fire. Such vehicles include tanks, aircraft, and ships....
carrying high velocity anti-tank guns as the best way to deal with the fast moving armour spearheads of the German Blitzkrieg
Blitzkrieg
For other uses of the word, see: Blitzkrieg Blitzkrieg is an anglicized word describing all-motorised force concentration of tanks, infantry, artillery, combat engineers and air power, concentrating overwhelming force at high speed to break through enemy lines, and, once the lines are broken,...
. The M10 was based on the chassis of the M4 Sherman
M4 Sherman
The M4 Sherman, formally Medium Tank, M4, was the primary tank used by the United States during World War II. Thousands were also distributed to the Allies, including the British Commonwealth and Soviet armies, via lend-lease...
but carried thinner although more sloped armour
Sloped armour
Sloped armour is armour that is neither in a vertical nor a horizontal position. Such "angled" armour is often mounted on tanks and other armoured fighting vehicles...
in order to comply with the high speed requirement for the tank. At the same time, the British had been examining the possibility of designing a low-silhouette self-propelled tank destroyer, preferably with a 360-degree traversing turret, with armour that would be able to resist the German 50 mm at 800 yards and mounting the 17 pounder. However with the arrival of the M10 on the battlefield in late 1942, British plans for a turreted self-propelled gun were cancelled.
The M10 was first made available to the British in 1943. These vehicles were open topped and mounted a 3" American gun, which was significantly more powerful than the Ordnance QF 6 pounder
Ordnance QF 6 pounder
The Ordnance Quick-Firing 6-pounder 7 cwt, or just 6 pounder, was a British 57 mm gun, their primary anti-tank gun during the middle of World War II, as well as the main armament for a number of armoured fighting vehicles...
that was mounted on British tanks of the period and was of equal power to the 7.5 cm KwK 40
7.5 cm KwK 40
The 7.5 cm KwK 40 was a German 7.5 cm Second World War era vehicle mounted gun, used as the primary anti-tank weapon of the German medium tank the SdKfz.161 Panzerkampfwagen IV and the SdKfz.142 Sturmgeschütz III assault guns ...
used by the Panzer IV
Panzer IV
The Panzerkampfwagen IV , commonly known as the Panzer IV, was a medium tank developed in Nazi Germany in the late 1930s and used extensively during the Second World War. Its ordnance inventory designation was Sd.Kfz...
and Sturmgeschütz III
Sturmgeschütz III
The Sturmgeschütz III assault gun was Germany's most produced armoured fighting vehicle during World War II. It was built on the chassis of the proven Panzer III tank...
. When introduced into service in late 1942, the thin but sloped armour of the M10 provided good protection against the standard 50 mm gun
5 cm KwK 39
The 5 cm KwK 39 L/60 was a German 50 mm caliber gun used during Second World War, primarily as the main armament of later variants of the German Panzerkampfwagen III tank between 1941-1942. It was developed as a variant of the towed gun 5 cm PaK 38...
mounted on most German tanks and anti-tank guns, and the 3 inches (76.2 mm) gun was able to easily defeat all German armour except for the handful of Tigers
Tiger I
Tiger I is the common name of a German heavy tank developed in 1942 and used in World War II. The final official German designation was Panzerkampfwagen Tiger Ausf. E, often shortened to Tiger. It was an answer to the unexpectedly formidable Soviet armour encountered in the initial months of...
deployed against the Western Allies.
Design
Ordnance QF 17 pounder
The Ordnance Quick-Firing 17 pounder was a 76.2 mm gun developed by the United Kingdom during World War II. It was used as an anti-tank gun on its own carriage, as well as equipping a number of British tanks. It was the most effective Allied anti-tank gun of the war...
, a gun with greatly superior anti-tank performance over the standard American 3" anti-tank gun.
The 17 pounder mounted on the Achilles was able to penetrate some 140 mm of armour at 500 m (546.8 yd) and 131 mm at 1000 m (1,093.6 yd) using standard Armour Piercing, Capped, Ballistic Capped
APCBC
The armour-piercing capped ballistic cap is a type of armor-piercing shell introduced in the 1930s.-Development:The APCBC munition type was an evolutionary development of the early war armour-piercing capped shell, itself an evolution of the more basic AP and APHE shell types...
(APCBC) ammunition impacting at a 30 degree angle. When supplied, Armour-piercing discarding sabot
Armour-piercing discarding sabot
Armour-piercing discarding sabot is a type of kinetic energy projectile fired from a gun to attack armoured targets. APDS rounds are sabot rounds and were commonly used in large calibre tank guns, but have now been superseded by armour-piercing fin-stabilized discarding sabot projectiles in such...
(APDS) ammunition could penetrate some 209 mm (8 inches) of armour at 500 metres and 192 mm at 1,000 metres at a 30 degree angle. In comparison the 3 inches (76.2 mm) gun on the standard M10 using the same type of ammunition (APCBC) would penetrate 98 mm of armour at 500 m at a 30 degree angle, and 88 mm of armor at 1,000 meters at a 30 degree angle. Only with High Velocity Armour Piercing (HVAP) ammunition did the 3 inches (76.2 mm) gun compare with the 17 pounder, the ammunition being able to penetrate 140 mm at 500 m at a 30 degree angle, and 127 mm at 1,000 m at a 30 degree angle. However HVAP ammunition was in very short supply and it only just compared with the standard 17 pounder ammunition that was available in huge amounts for the British.
The 17 pounder required a counterweight fitted behind the muzzle brake
Muzzle brake
Muzzle brakes and recoil compensators are devices that are fitted to the muzzle of a firearm or cannon to redirect propellant gases with the effect of countering both recoil of the gun and unwanted rising of the barrel during rapid fire...
on its long barrel. This gave the Achilles a distinctive appearance compared to the M10 and there were attempts to disguise this by painting the brake and counterweight.
The only other change carried out on the Achilles was the addition of 17 mm (0.669291338582677 in) thick armour plates welded to the front and sides of the M10 to increase armour protection, as well as a 20 mm thick shield fitted to the top of the turret to provide protection from overhead threats that resulted from the M10 having an open top turret.
Production
76 mm gun M1
The 76 mm Gun M1 was an American Forces World War II-era tank gun, which replaced the 75 mm gun on late Medium tank M4s, and was used for all 76 mm Gun Motor Carriage M18 tank destroyers. The previous 75 mm M3 L/40 gun on the early M4 Sherman variants was designed more as an infantry support...
. This gun mounting design allowed for the British to replace the 3 inch gun with the 17 pounder gun. The British took delivery of some 845 vehicles in 1943, but of the second version of the M10, only the T71 mark could carry the 17 pounder, the T70 mark being designed to only allow the lighter American 76.2mm M1 gun.
The British had planned to convert some 1,000 M10s into 17pdr armed variants for Normandy, but for some reason conversions were not started until April 1944. By D-Day only some 124 M10s had been converted, however the number of conversions post D-day increased and by the end of the year 816 M10s had been converted, 152 vehicles in November alone. However the low numbers at D-day meant that many British units went ashore fielding standard M10s rather than 17 pounder armed Achilles, and losses in Achilles units could at times be hard to replace, the crews receiving regular 3" armed M10s as replacements for their lost 17 pdr Achilles much to their dismay.
As a self-propelled anti-tank gun, Achilles as well as standard M10s were distributed to and operated by the regiments of the Royal Artillery
Royal Artillery
The Royal Regiment of Artillery, commonly referred to as the Royal Artillery , is the artillery arm of the British Army. Despite its name, it comprises a number of regiments.-History:...
. Around 1,650 M10 tank destroyers were received by the British during the war, of these 1,100 were converted to the 17 pdr by the end of the war.
Operational use
Panzer IV
The Panzerkampfwagen IV , commonly known as the Panzer IV, was a medium tank developed in Nazi Germany in the late 1930s and used extensively during the Second World War. Its ordnance inventory designation was Sd.Kfz...
and Sturmgeschütz
Sturmgeschütz
Sturmgeschütz is a German word for "assault gun", usually abbreviated StuG. The vehicle was a leading weapon of the Sturmartillerie, a branch of the German artillery tasked with close fire support of infantry in infantry, panzer, and panzergrenadier units...
with regular ammunition but not the heavier Tigers and Panthers
Panther tank
Panther is the common name of a medium tank fielded by Nazi Germany in World War II that served from mid-1943 to the end of the European war in 1945. It was intended as a counter to the T-34, and to replace the Panzer III and Panzer IV; while never replacing the latter, it served alongside it as...
. The next generation British gun, the 17 pounder anti-tank gun, was able to deal with Tigers and Panthers but was a heavy and unwieldy weapon that could take over 12 hours to move into position, dig in and camouflage. The British knew from experience that the Germans would quickly counterattack and it took too long to set up the 17 pounders before the German heavy tanks could overrun the infantry's position.
Churchill tank
The Tank, Infantry, Mk IV was a heavy British infantry tank used in the Second World War, best known for its heavy armour, large longitudinal chassis with all-around tracks with multiple bogies, and its use as the basis of many specialist vehicles. It was one of the heaviest Allied tanks of the war...
units as they did not have associated 17 pdr armed tanks like Sherman
M4 Sherman
The M4 Sherman, formally Medium Tank, M4, was the primary tank used by the United States during World War II. Thousands were also distributed to the Allies, including the British Commonwealth and Soviet armies, via lend-lease...
and Cromwell tank
Cromwell tank
Tank, Cruiser, Mk VIII, Cromwell ,The designation as the eighth Cruiser tank design, its name given for ease of reference and its General Staff specification number respectively and the related Centaur tank, were one of the most successful series of cruiser tanks fielded by Britain in the Second...
troops did.
Achilles went ashore on D-Day, equipping units of the Royal Artillery
Royal Artillery
The Royal Regiment of Artillery, commonly referred to as the Royal Artillery , is the artillery arm of the British Army. Despite its name, it comprises a number of regiments.-History:...
and Royal Canadian Artillery
Royal Regiment of Canadian Artillery
The Royal Regiment of Canadian Artillery is the artillery personnel branch of the Canadian Forces .-History:...
in Armoured Division or Corps Anti-tank Regiments. A typical A/Tk Regiment would have 4 Batteries, 2 x Towed 17 Pdr Batteries, 1 x Achilles and 1 x M10 Battery. The M10 Battery was replaced by a second Achilles Battery as more vehicles became available. Perhaps the most successful action of the Achilles was conducted by B troop, 245th Battery, 62nd Anti-Tank Regiment, Royal Artillery attached to the Hamilton Light Infantry
The Royal Hamilton Light Infantry (Wentworth Regiment)
The Royal Hamilton Light Infantry is a Primary Reserve unit of the Canadian Forces based at John W. Foote VC Armouries in Hamilton, Ontario....
during Operation Charnwood
Operation Charnwood
Operation Charnwood was a Second World War Anglo-Canadian offensive that took place from 8–9 July 1944, during the Battle of Normandy. The operation was intended to at least partially capture the German-occupied French city of Caen , which was an important Allied objective during the opening stages...
. South of Buron, a counterattack by a mixed force of Panzer IV
Panzer IV
The Panzerkampfwagen IV , commonly known as the Panzer IV, was a medium tank developed in Nazi Germany in the late 1930s and used extensively during the Second World War. Its ordnance inventory designation was Sd.Kfz...
and Panther tank
Panther tank
Panther is the common name of a medium tank fielded by Nazi Germany in World War II that served from mid-1943 to the end of the European war in 1945. It was intended as a counter to the T-34, and to replace the Panzer III and Panzer IV; while never replacing the latter, it served alongside it as...
s of the 12th SS Panzer Regiment was defeated by Achilles and 17-pounder anti tank guns
Ordnance QF 17 pounder
The Ordnance Quick-Firing 17 pounder was a 76.2 mm gun developed by the United Kingdom during World War II. It was used as an anti-tank gun on its own carriage, as well as equipping a number of British tanks. It was the most effective Allied anti-tank gun of the war...
of 245th Battery, 62nd Antitank Regiment. Thirteen German tanks were destroyed in one of the most successful antitank engagements of the campaign, for the loss of four tank destroyers and a further four damaged.
See also
- Archer (tank destroyer)Archer (tank destroyer)The SP 17pdr, Valentine, Mk I, Archer was a British self propelled anti-tank gun of the Second World War based on the Valentine infantry tank chassis fitted with a Ordnance QF 17 pounder gun.-Design and development:...
- a 17 pdr gun in a fixed position on a Valentine tank chassis.