Sherman Firefly tank

The Sherman Firefly tank was a British conversion of the American M4 Sherman, fitted with the powerful 17-pounder anti-tank gun in place of the Sherman’s 75 mm gun, and it was the only Allied tank in Normandy that could reliably defeat the German Tiger and Panther at normal combat ranges. About 2,100 Fireflies were built, and they served in British, Canadian, and Polish armoured units, where they were prized by their crews and feared by German tankers, who learned to target them first.

1. Key Facts

Field	Value
Type	Medium tank (Sherman conversion)
Country	United Kingdom (based on American M4 Sherman)
Service period	1944–1945 (Second World War); post-war to 1950s
Production	About 2,100 converted
Weight	About 33–34 tons
Length	6.06 metres (19.9 feet) hull; 7.7 metres with gun
Width	2.62 metres (8.6 feet)
Height	2.75 metres (9 feet)
Crew	4 (commander, gunner, loader, driver; later 5 with hull gunner removed)
Main armament	17-pounder (76.2 mm) QF gun
Secondary armament	.30-calibre Browning machine gun (coaxial); .50-calibre on turret
Armour	12–75 mm (hull front 51 mm; turret front 76 mm)
Engine	Chrysler Multibank or Ford GAA, 400–500 horsepower
Speed	40 km/h (25 mph) on roads
Range	About 160 km (100 miles) on roads
Main theatres	Normandy; North-West Europe; Italy

2. Development and Design

The Need for a Gun That Could Kill Tigers

The Sherman Firefly was born of a problem that became clear in 1942 and 1943, when British and American tanks met the German Tiger and Panther, and found that their 75 mm guns could not penetrate the frontal armour of these tanks at normal ranges. The British had a gun that could, the 17-pounder, which was the most powerful anti-tank gun in Allied service, but it was a large, heavy weapon, designed for use as a towed gun, and it was not clear whether it could be fitted into a tank turret. The British engineer George Witheridge, working at the Lulworth gunnery school, proposed fitting the 17-pounder into the Sherman, which had a large turret ring and a roomy turret, and after experiments, the design was found to work, although it required extensive modifications to the gun and to the turret.

Fitting the 17-Pounder into a Sherman

Fitting the 17-pounder into the Sherman was a difficult engineering task, for the gun was longer and heavier than the 75 mm gun, and its breech was too large for the Sherman turret. The designers, led by Witheridge and by the Royal Armoured Corps, modified the gun by turning it on its side, so that the breech opened sideways, and by shortening the recoil, and they fitted a new radio in an armoured box on the back of the turret, to make room for the larger gun. The loader had to work in a cramped turret, and the gun had a long barrel that stuck out well beyond the front of the tank, which made the Firefly easy to recognise, but the result was a tank that could defeat any German tank at ranges of up to 1,500 metres. The first Fireflies were delivered in early 1944, just in time for D-Day, and they were issued to British and Canadian armoured regiments at a rate of one per troop of four tanks.

The Sherman Chassis and Conversion

The Firefly was based on the Sherman M4 and M4A4, with the American-built hull and the Chrysler Multibank or Ford engine, and the conversion was carried out in British workshops, where the 75 mm gun was removed and the 17-pounder was installed. The conversion also involved removing the hull machine gunner, whose position was used to store 17-pounder ammunition, and fitting a new gun sight and a new mantlet. The Firefly retained the Sherman’s reliability and its ease of maintenance, which were valued by its crews, and it had the same mobility and the same armour as a standard Sherman, although the long gun made it nose-heavy and affected its balance.

3. Technical Specifications

The 17-Pounder Gun

The 17-pounder was a 76.2 mm gun with a muzzle velocity of about 900 metres per second with armour-piercing capped ballistic capped ammunition, and it could penetrate about 130 mm of armour at 1,000 metres, which was enough to defeat the frontal armour of a Panther and the side armour of a Tiger. With armour-piercing discarding sabot ammunition, which was introduced later in the war, the gun could penetrate even more, although this ammunition was less accurate at long range. The gun fired a 7.7-kilogram armour-piercing shell, and it had a high rate of fire, although the loader had to work hard in the cramped turret. The Firefly carried about 77 rounds of 17-pounder ammunition, which was stowed in the hull and in the turret, and the gun had an elevation of 20 degrees and a depression of 5 degrees.

Engine, Mobility, and Armour

The Firefly used the same engines as the Sherman, with the Chrysler Multibank producing 425 horsepower and the Ford GAA producing 500 horsepower, giving a top speed of 40 kilometres per hour on roads and a range of about 160 kilometres. The suspension was the Sherman’s vertical volute spring system, which gave a good ride and was easy to maintain, and the tank could cross trenches of 2.2 metres and climb slopes of 30 degrees. Armour protection was the same as a standard Sherman, with 51 mm on the hull front, 38 mm on the sides, and 76 mm on the turret front, which was adequate against most German anti-tank guns but not against the 88 mm gun of the Tiger. The Firefly was, like the Sherman, vulnerable to German guns, and its survival depended on firing first and on using cover.

Crew and Fighting Compartment

The Firefly had a crew of four, a commander, a gunner, a loader, and a driver, with the hull machine gunner removed to make room for ammunition. The commander sat in the turret, with the gunner and loader, and the driver sat in the front of the hull, and the crew worked in a cramped but well-organised compartment. The long barrel of the 17-pounder made the tank easy to identify, and German tank crews learned to target Fireflies first, so British crews often painted the front half of the barrel to make it look like a standard 75 mm gun, a trick that sometimes worked. The Firefly was also fitted with a .50-calibre machine gun on the turret roof for anti-aircraft defence, and a coaxial .30-calibre machine gun for use against infantry.

4. Combat Service

Normandy and the First Battles

The Firefly first saw combat in Normandy in June 1944, where it served with British and Canadian armoured divisions, and where it quickly proved its value, destroying German tanks that standard Shermans could not touch. The Firefly was used in the battles for Caen, for Villers-Bocage, and for the Falaise Pocket, where it engaged Panthers and Tigers at long range and destroyed them. The most famous Firefly action was at Villers-Bocage, where a Firefly of the 4th County of London Yeomanry is credited with destroying the Tiger of the German ace Michael Wittmann, although this claim is disputed, and other British tanks and anti-tank guns may have been responsible. The Firefly also served in the breakout from Normandy and in the advance across France, where it was used to provide anti-tank cover for the advancing columns.

North-West Europe and the Final Campaigns

After Normandy, the Firefly served in Belgium, the Netherlands, and Germany, where it fought in the battles for Arnhem, for the Reichswald, and for the Rhine crossing, and where it continued to be the most effective Allied tank against German armour. The Firefly also served in Italy, where it was used by British and Commonwealth forces, and where its 17-pounder gun was effective against German tanks in the mountainous terrain. By the end of the war, the Firefly had earned a reputation as the best Allied tank killer, and its crews were proud of their vehicle, even though they knew that German tankers targeted them first.

Post-War Service

After the war, the Firefly remained in service with the British Army and with other armies, including those of Canada, the Netherlands, and several South American countries, and it was used in training and in second-line roles into the 1950s. The Firefly was eventually replaced by the Centurion tank, which had a 17-pounder gun and later a 20-pounder gun, and which was a far more capable tank, but the Firefly is remembered as a wartime expedient that worked, a tank that was built quickly and that filled a vital gap in Allied armour.

5. Variants

The Firefly Based on Different Shermans

The Firefly was built on several Sherman variants, with the most common being the Sherman VC, based on the M4A4 with the Chrysler Multibank engine, and the Sherman IC, based on the M4 with a different engine. There were also Fireflies based on the M4A1 and M4A3, although these were less common, and the differences between the variants were mainly in the engine and in the hull, rather than in the gun. All Fireflies had the same 17-pounder gun and the same turret modifications, and they were all issued at a rate of one per troop, with three standard Shermans and one Firefly in each troop of four tanks.

The Firefly and the Sherman Hybrid

The Firefly was also built on the Sherman Hybrid, a version with a cast front hull and a welded rear hull, which was produced in the United States and which was used by British forces. The Hybrid Firefly was similar to other Fireflies, but it had a slightly different hull shape and a different engine. The Firefly was a conversion, not a new design, and it was built in British workshops, with the guns and the turrets modified by hand, which meant that there were small differences between individual vehicles.

The Firefly in Foreign Service

After the war, Fireflies were exported to several countries, including Argentina, where they served into the 1970s, and the Netherlands, where they were used for training. The Firefly was also used by the Canadian Army, which had used it in Normandy and which kept it in service after the war. The widespread use of the Firefly shows its reputation as an effective tank killer, and its longevity in foreign service is a testament to the soundness of the Sherman chassis and the power of the 17-pounder gun.

6. Strengths

The 17-Pounder Gun

The great strength of the Firefly was its 17-pounder gun, which was the most powerful tank gun in Allied service, and which could defeat any German tank at normal combat ranges. The gun gave British and Canadian armoured units a weapon that could kill Tigers and Panthers, and it boosted the morale of crews who had previously felt outgunned by German tanks. The Firefly’s gun was also accurate and reliable, and it had a high rate of fire, which allowed its crews to engage multiple targets quickly.

Reliability and Availability

The Firefly retained the Sherman’s reliability and its ease of maintenance, which were valued by its crews, and it was available in sufficient numbers to equip every armoured troop with one Firefly, which meant that every troop had a tank that could kill a Tiger. The Firefly was also easy to supply, since it shared parts with the Sherman, and it could be maintained by the same mechanics and with the same tools. This availability was a major advantage, for the Firefly could be built quickly and in large numbers, unlike the heavier British tanks that were still in development.

Morale and Reputation

The Firefly had a powerful effect on morale, for its crews knew that they had a gun that could kill any German tank, and German tankers knew that the Firefly was a threat, and they targeted it first. The Firefly’s reputation as a Tiger killer spread quickly, and it became a symbol of British ingenuity, a tank that was improvised in a workshop and that proved to be one of the best Allied tanks of the war. German prisoners interrogated after Normandy reported that their tank crews had been ordered to engage Fireflies first, a compliment that British crews learned of with mixed feelings, since it made their tanks priority targets.

7. Weaknesses

Thin Armour and Vulnerability

The main weakness of the Firefly was its thin armour, which was the same as a standard Sherman, and which could not stop the 88 mm gun of a Tiger or the 75 mm gun of a Panther. The Firefly was vulnerable to German tanks, and its crews knew that if a German tank fired first, they would likely be killed. The long barrel of the 17-pounder also made the Firefly easy to identify, and German tankers learned to shoot at Fireflies first, which made the vehicle a priority target.

Cramped Turret and Muzzle Flash

The Firefly’s turret was cramped, with the large 17-pounder gun taking up most of the space, and the loader had to work hard to load the gun quickly. The gun also produced a large muzzle flash and a cloud of smoke, which revealed the tank’s position and made it difficult to see the target after firing. The Firefly was also nose-heavy, with the long gun affecting its balance, and it was slower to traverse the turret than a standard Sherman.

Limited Numbers and the One-Per-Troop Rule

The Firefly was issued at a rate of only one per troop of four tanks, which meant that most Allied tanks in Normandy were still standard Shermans with 75 mm guns that could not kill a Tiger. The Firefly was a valuable asset, but it was not available in sufficient numbers to equip every tank, and its crews had to be protected by the other tanks in the troop, which was a difficult task in combat. The shortage was caused by the limited supply of 17-pounder guns and by the time required for the conversion, and it was not until late 1944 that some regiments received a second Firefly per troop.

8. Comparison with Rivals

Against the Standard Sherman

Compared with the standard Sherman, the Firefly was superior in firepower, with the 17-pounder gun able to defeat any German tank, while the 75 mm gun could not penetrate the frontal armour of a Panther or a Tiger. The Firefly was, however, the same as the Sherman in armour, mobility, and reliability, and it was more cramped and easier to identify. The Firefly was a better tank killer, but it was not a better tank overall, and it was used alongside standard Shermans, with the Firefly providing the anti-tank punch and the Shermans providing the numbers.

Against the Tiger and Panther

Against the Tiger and the Panther, the Firefly was inferior in armour and in protection, but it was equal or superior in firepower, and it could kill either tank at ranges where the German tanks could kill it. The Firefly’s advantage was its gun, and its disadvantage was its armour, and the outcome of a duel depended on who fired first and who had the better position. The Firefly was a match for the Tiger and the Panther in firepower, but not in protection, and its crews had to use skill and tactics to survive.

Against the Cromwell and Churchill

Against the Cromwell, the British cruiser tank, the Firefly was superior in firepower, although the Cromwell was faster and more manoeuvrable. Against the Churchill, the British infantry tank, the Firefly was faster and better armed, although the Churchill had thicker armour and was better suited to infantry support. The Firefly was the best British tank killer of the war, and it filled a gap that no other British tank could fill. The Cromwell was faster and more reliable, and the Churchill had thicker armour, but neither could penetrate a Panther’s frontal plate at combat range, which left the Firefly as the only British tank that could be relied on to kill German heavy armour.

9. Legacy

The Tiger Killer of Normandy

The legacy of the Sherman Firefly is its reputation as the Tiger killer of Normandy, a tank that gave Allied crews a weapon that could defeat the most feared German tanks, and that played a vital role in the battles of 1944 and 1945. The Firefly is remembered in Britain and in Canada with pride, and it is preserved in museums, including the Bovington Tank Museum in England, where visitors can see the tank that once faced Tigers and Panthers in Normandy.

A Wartime Expedient That Worked

The Firefly is also remembered as a wartime expedient that worked, a tank that was improvised in a workshop, using a gun that was not designed for a tank, and that proved to be one of the most effective Allied tanks of the war. The Firefly showed the value of ingenuity and of rapid adaptation, and it influenced later British tank design, particularly the Centurion, which was designed with a powerful gun from the start. The Firefly deserves its place in history as a symbol of British engineering and of the courage of its crews.

Remembering the Firefly Crews

The crews of the Firefly are remembered for their skill and their bravery, and for the battles they fought in Normandy and in North-West Europe, where they faced German tanks that outmatched them in armour and in protection. The Firefly crews, many of whom were lost, deserve to be remembered alongside the tankers of the Sherman and the Cromwell, for they too fought in the liberation of Europe, and they too paid the price. Firefly crews in Normandy often fought with their long barrels camouflaged to resemble ordinary Shermans, a small deception that sometimes bought them the few seconds they needed to fire first.

Frequently Asked Questions

How many Sherman Fireflies were built?
About 2,100 Fireflies were converted from Sherman tanks in British workshops, and they served with British, Canadian, and Polish armoured units in Normandy and North-West Europe.

What gun did the Firefly carry?
The Firefly carried the British 17-pounder (76.2 mm) gun, which could penetrate about 130 mm of armour at 1,000 metres, enough to defeat the frontal armour of a Panther and the side armour of a Tiger.

Could the Firefly kill a Tiger tank?
Yes, the Firefly could kill a Tiger, particularly from the side or at close range, and it was the only Allied tank in Normandy that could reliably defeat Tigers and Panthers at normal combat ranges.

Did a Firefly kill Michael Wittmann?
A Firefly of the 4th County of London Yeomanry is credited with destroying Wittmann’s Tiger at Villers-Bocage, although the claim is disputed and other British tanks and anti-tank guns may have been responsible.

How was the Firefly different from a standard Sherman?
The Firefly had a 17-pounder gun in place of the 75 mm gun, a modified turret with a radio box on the back, no hull machine gunner, and a much longer barrel that made it easy to identify.

Did the Firefly serve after the Second World War?
Yes, the Firefly served with the British Army and with foreign armies, including Argentina and the Netherlands, into the 1950s and, in some cases, into the 1970s.

Sources

• David Fletcher, Sherman Firefly (Osprey, 2008)
• Mark Hayward, Sherman Firefly (Barbarossa Books, 2001)
• The Tank Museum, Bovington, Firefly collection
• Steven J. Zaloga, Armored Victory 1945 (2012)
• The Canadian War Museum, Firefly collection