Then again, there was no real need for it to slow down at all — it was practically invulnerable to bombardment at speed, and by the time an air strike could be called in, the British gun could be many kilometres away and completely out of range should they decide to continue on rather than halt within the tunnel. Obergruppenführer Paul Strasser had other plans however, and had no intention of allowing the last of their targets escape.
“Gustav… new target…!” He quickly barked the order at his plotters, the experienced artillerymen immediately verifying their coordinates with their FAC flying above Dover before quickly working out their new firing solutions and passing the information on to Gustav’s gun crew. “Dora… mission change! Clear breech and load VRRD round!”
Those orders were also passed on instantly, and within seconds there was a complete halt to the reloading process within Dora’s gunpit. The high explosive shell halfway through being rammed into the gun’s breech was hoisted out of the way by a heavy-duty loading crane as the main ammunition lift was lowered to the waiting crew below, only to return a moment later with a gigantic, ‘needle-pointed’ armour piercing round almost four metres long and weighing almost seven tonnes.
Piecemaker and her crew powered into the northern mouth of the tunnel at a steady forty kilometres per hour. Pruitt and the others inside the driver’s cab could see the dim flicker of light at far end, now just 1,200 metres away and drawing nearer at a fast pace. Initial plans had been to shelter inside the tunnel itself, but Pruitt had countermanded that order and instead directed the driver to continue on to the west toward Canterbury and more certain safety. So long as they kept moving, there was little chance the German guns could zero on them accurately, and keep moving was exactly what Pruitt intended to do.
All of them heard and felt the impact of another huge shell seconds later, although there was no way to tell where it had landed from their position underground. It was only as the tunnel mouth ahead drew ever closer that the first evidence of thick smoke became visible against the open landscape beyond. The strike wasn’t close — that much was clear from what little they could see — and for a second or two it seemed strange that even despite their speed the shot should’ve been so far off course.
It was only a few more seconds however before they all realised the shot had in fact been right on target. Guston Tunnel had been gouged out of the surrounding landscape and as a result, each end opened into a deep, steep sided cutting that trains gradually climbed out of heading away in either direction. Gustav’s latest shell hadn’t landed a direct hit on the mouth of the tunnel — it hadn’t needed to. Instead, 4,800kg of pointed steel and high explosive travelling at over 800 metres per second had simply been aimed at the cutting beyond, and it had been a perfect shot.
A narrow country lane crossed above the tracks a little more than three hundred metres past the tunnel mouth, supported by a short stone bridge. The shell had landed just a few dozen metres away, punching into the upper edge of the western side of the cutting and blasting away a thirty metre hole. The bridge collapsed immediately, dumping huge stone blocks and rubble across both sets of tracks in an impenetrable wall. The driver hit the brakes as heavily as he dared without risking immediate derailment and brought the train to a shuddering halt just forty metres from the opening as dust and smoke from the explosion rolled down the tunnel past the train in an acrid, choking wash of heat.
A little more than thirty-eight thousand metres away, super-heavy gun SK-100(E) ‘Dora’ fired a specially-loaded shell that was known to the Wehrmacht as a 80cm VRRD. The acronym stood for verlängertereihe rüstungsdurchstossen, and roughly translated into English as ‘Extended Range Armour-Piercing’. The huge gun’s conventional armour piercing shell (if anything about the weapons could be considered ‘conventional’) weighed more than seven tonnes and was designed to penetrate seven metres of reinforced concrete. The extended range version looked almost identical, but weighed 350kg less and was equipped with a special feature that in post-war Realtime would become known as ‘base-bleed’ technology.
The base of the VRRD shell was slightly recessed instead of tapering to a flat bottom, and a flare-like mechanism into was fitted the resultant cavity that generated a small but significant amount of inert gas. The gas created filled the small area of vacuum that normally occurred at the very base of an artillery shell — a vacuum that brought with it a significant amount of aerodynamic drag. By eliminating that vacuum (and the drag it created), the VRRD or ‘base-bleed’ shell was able to extend its range by approximately thirty percent.
A standard 80cm HE shell could reach approximately 48km range (and its own VRHE version out to better than 62km), but the conventional armour-piercing round, being more than two tonnes heavier, could make barely 38km, and at the very boundary of its extreme range it couldn’t hope to hit its intended target with anything close to the necessary accuracy. The VRRD variant however could reach out to almost 50km, and as such the Guston Tunnel was still close enough to allow excellent accuracy, if with a minor reduction in explosive and penetrative performance due to its slightly reduced weight.
Oblivious to all the technology and design surrounding it, the shell itself flew on through the clear sky on its supersonic ballistic arc, reaching the zenith of its journey high above the middle of The Channel. Far too heavy to be even the slightest bit affected by wind or turbulence around it, it tipped back toward Earth and the green fields of Kent far below.
Dora’s shell went long, completely by chance landing on the exact centre of the intersection of the A2 with Dover Road, three hundred metres to the north. The shell punched deep into the soft earth before exploding too far down to reach the open air above. Instead, the blast created a large, artificial underground cavern beneath the surface known as a camouflet, into which the land above immediately collapsed. A roughly circular section of intersection and surrounding land approximately five metres across immediately fell into the newly-formed space, leaving a crater several metres deep.
Inside Guston Tunnel, everyone felt and heard the impact. The earth shook dramatically and a shower of earth, dust and some larger fragments of brickwork rained down on the train and their heads as the structure shuddered under the nearby blast. They couldn’t see the cracks that had appeared in the darkness of the tunnel roof above their heads, but they could hear the shifting and grating sounds of movement overhead, and the larger chunks that fell about them were a terrifying warning that all was definitely not well.
“The boys are going to make a break for it, sir!” Lieutenant Carstairs, his 2IC, was clearly terrified as he clambered up the side of the locomotive and into the cabin to confront his commanding officer.
“We can’t afford to get caught in the open out there,” Pruitt replied, also frightened but forcing himself to remain in control. “That cutting’s a death-trap for a hundred yards beyond the tunnel in either direction: we’re done for if the Luftwaffe catches us.”
“One more hit like that and we’re done for anyway!” Carstairs shot back, his voice almost breaking under the strain and fear. “I’d rather take my chances with Jerry fighters than with these bloody ‘superguns’!”
Unable to reach HQ on the radio from inside the tunnel, Major Sebastian Pruitt was left to make his own decisions and he needed to make one quickly. The sides of the cutting at either end of the tunnel were far too steep for he or his men to have any hope of climbing to safety, and that situation continued on for some distance before the tracks levelled out into open fields. Pruitt wasn’t about to allow his men to become trapped in such a fashion. That being said, as he craned his head out through the open doorway of the driver’s cab and stared back down along the length of the train, he could already see some of his men jumping from the gun and making their way toward the far end.