The Sherman Firefly was a British modification of the American M4 Sherman. By fitting it with a powerful anti-tank gun, the Firefly could effectively take on heavily armored German tanks like the Panther and Tiger. This upgrade made the Firefly a crucial asset for the Allies, helping to take on the strong German armour.
Concept:
Around 1943, during World War II, the M4 Sherman was a top tank for the Allies, outperforming the German Panzer IIIs and IVs. However, it began to lose its edge against newer German tanks like the Tiger I and Panther, which had better firepower and better armor. To enhance the Sherman’s firepower, the Americans upgraded to a 76 mm gun, while the British chose the powerful 17-pounder anti-tank gun. The upgraded Sherman with the 17-pounder would be known as the Firefly.
Development:
W.G.K. Kilbourn, a professional engineer at Vickers, was tasked with fitting the 17-pounder gun into the Sherman tank’s turret. This task required significant modifications to the gun and turret. Kilbourn shortened the recoil cylinders and mounted them on the sides of the gun. He also modified the gun barrel to fit on a special cradle and ensured the gun breech opened horizontally. Contrary to popular belief, the gun was not simply rotated 90 degrees.
The redesigned 17-pounder gun, named Mk IV, was successfully built on November 11, 1943, and fitted into the Sherman turret. However, the modifications led to space constraints inside the turret. To address this, Kilbourn added a hatch for the loader and moved the radio to an armoured box on the turret’s rear. This box also acted as a counterweight for the longer, heavier gun.
Ammo storage was another challenge, as the 17-pounder rounds were larger and heavier than the original 75mm shells. The crew stowed some rounds in bins in the turret and under the turret floor, accessible only when the turret was aligned a certain way. To increase ammo storage, the bow machine gunner and his machine gun were removed, and a rack holding 15 rounds was placed in his position. However, one slot was difficult to access, reducing the total usable storage to 14 rounds.
Conversions:
On 6 January 1944, the completed Sherman with the 17-pounder gun was inspected. The War Office required up to 2,100 Shermans to be upgunned. Only Shermans with petrol engines, M34A1 gun mounts, and hydraulic turret traverse systems were eligible for conversion. This included Sherman I (M4), Sherman I Hybrid (M4 “Composite”), and Sherman V (M4A4). Sherman II (M4A1) and Sherman III (M4A3) were also technically eligible, but information on Sherman II is scarce, and Sherman III were allocated to the U.S. Army, leaving none for British conversion.
Tanks with the 17-pounder were designated with a “C” in their mark number, like “Sherman VC” for M4A4 with the conversion. Troops began calling these upgunned Shermans “Firefly” by March 1944, likely due to the prominent muzzle flash of the 17-pounder.
Special Variant:
The Firefly was also upgraded into a new tank called the Firefly 'Tulip'. This Firefly was loaded with 60lb RP-3 air-to-ground aircraft rockets that were normally fitted to planes such as the Typhoon, Hurricane, Mosquito, Swordfish and Beaufort. This was a Canadian idea to increase the firepower of their tanks.
Combat Usage:
The Firefly’s first combat action on D-Day (6 June 1944) occurred at sea, where it was assigned to fire over the berm towards concrete fortifications from landing craft tanks (LCTs). Six Fireflies were divided into pairs and assigned to DD tank regiments of the British 13th/18th Hussars at Sword Beach, and the Canadian 1st Hussars and Fort Garry Horse at Juno Beach. The 13th/18th Hussars did not fire their Fireflies on the way in, but the 1st Hussars had positive experiences with the Fireflies in rough weather. Upon reaching the shore, the Fireflies disembarked, cleared obstacles, and rejoined their original tank regiments.
The first non-DD tank regiment to land with Fireflies was the Staffordshire Yeomanry, which had at least 12 Sherman VC tanks alongside 48 Sherman IIIs. Little information exists on their performance during the opening days of the Normandy campaign. Other regiments originally equipped with DD tanks and Fireflies were used as regular tank regiments once inland. The Sherwood Rangers Yeomanry deduced a few days after the landings that the Germans were targeting Fireflies specifically for their longer guns. Despite this concern, evidence showed that 19% of Fireflies and 29% of regular tanks were lost.
By 23 June 1944, only six replacement Fireflies had arrived despite 22 losses. High demand for Fireflies led to changes in unit organization, with one Firefly per tank troop instead of one per three Shermans. Some commanders considered using 17-pounder armed M10s as supplements. Fireflies were crucial in Normandy as they could defeat German Panther and Tiger tanks. Notably, a Firefly likely destroyed the Tiger tank of Tiger Ace Michael Wittmann on 8 August 1944.
The Firefly served in the British Armies in the European Theater until May 1945 being shared around among Polish, Canadian, New Zealand, British, and South African regiments. When they were retired with the end of the war and replaced by better designs like the Comet cruiser tank and the Centurion tank.
Bibliography:
- Fletcher, David. Sherman Firefly Great Britain: Osprey Publishing Ltd., 2008. Kindle Edition
- Hunnicutt, R.P. Sherman: A History of the American Medium Tank U.S.A.: Feist Publications, 1978
- Morans, Nicholas. Inside the Chieftain’s Hatch: Sherman VC “Firefly” part 2 YouTube, 20 Mar. 2017. Web. 29 Mar. 2017.
- Zaloga, Steven J. M4 (76mm) Sherman Medium Tank 1943-65 Great Britain: Osprey Publishing Ltd., 2003. Kindle Edition
- Zaloga, Steven J. Armored Thunderbolt: The U.S. Army Sherman in World War II U.S.A: Stackpole Books, 2008. Kindle Edition
- Zaloga, Steven J. Armored Champion: The Top Tanks of World War II U.S.A: Stackpole Books, 2015. Kindle Edition
