The nickname "Ronson", after the cigarette lighter, is often applied to Sherman’s "because they light the first time". The trouble is the Ronson company didn't use that slogan until several years after the Second World war. The closest anyone has found is this advert from the 1950's.
In mid 1943 the three main western allies held a conference about flamethrowers. The result showed that the US were trailing behind the other two nations, this spurred the US army to accelerate its attempts at flamethrowing vehicles. Earlier in the year the US had seen a demonstration of the Churchill Crocodile. Suitably impressed the US delegation was informed that the Crocodile kits should be able to be fitted to M4 Shermans. This would mean the US forces wouldn't have had to take on a foreign vehicle. Towards the end of 1943 the US army started sounding out the British on the idea of Sherman Crocodiles, requesting that about 100 Shermans should be converted. The British then provided a wooden mock up for the US officers to view, whom in turn agreed that the design should be prototyped. At the start of 1944, after seeing a demonstration the US placed an order for 115 conversions, although in reality only four would be completed.
For the modellers out there, it should be noted that the British were to provide common parts of the Crocodile design, so its likely the components would be painted in S.C.C. 15 Olive Drab, which as you know weathers differently to the US colour. Of course the US may have repainted the British parts with standard US colours, so pick whichever you think looks best.
I believe this is the mock up. Note the early mud guards and odd looking flame gun compared to later photographs.
The crews who received the kits were less than thrilled at the idea of adding more fuel to a tank that was already regarded as a fire trap. Equally all the extra tanks and fuel canisters made evacuation from the tank harder, with the bow gunners hatch being partially blocked by one of the pressure cylinders. The emergency alternative escape hatch was blocked by a fuel tank.
Its target was a German held bunker. The stated range of 70 yards quickly turned out to be false. The Sherman had to advance to within 25 yards before the flame could hit the bunker. Even then it was utterly ineffective and the Germans remaining inside their bunker were not harmed. The after action report suggested that for some unknown reason the flamethrower wasn't firing at the correct pressure. This problem was to plague the E4-5 system, along with a tendency to fail to ignite. This happened to the 743rd tank battalion near the Roer river, when a E4-5 flamed a group of Germans occupying a roadside ditch. The Germans were soaked by a wet burst of flame fuel. In the same operation a E4-5 did show what it could do, when it was used to flush out German defenders occupying a house on a hill. The slope of the hill meant that the Sherman’s could only shoot at the upper floors of the house. But the flamethrower could place effective fire on the lower floors by lobbing the fuel over the crest of the hill. It forced the Germans to evacuate the position.
Churchill Crocodiles assaulting Brest. The two Shermans halted on the edge of the moat and incinerated the positions facing them. The Germans were forced to retreat from the area. The Two Shermans then pummelled the main gate with their 75mm's, blasting it open. Then the tanks clanked slowly across the bridge, with their trails of fuel bouncing along behind them. Once inside they set about burning everything, the bright tongues of flame spearing through the billowing smoke.