June 7th, 1944 1430 hours a fortified village three miles   inland from Sword Beach Normandy Oberfeldwebel   Karl Brenner commanded a  reinforced concrete pillbox   positioned to cover the main  road through the village   the position was excellent walls one meter thick   firing slits that provided  overlapping fields of fire   with adjacent bunkers ammunition stores   sufficient for sustained defense his squad had held this position for 18 months   turning back probe attacks and repelling reconnaissance patrols

the British had been ashore for barely 30 hours and Brenner was confident   his pillbox would stop them as it had stopped every previous assault   the British infantry advanced cautiously using ruined buildings for cover   Brenner’s machine gunner opened fire forcing them back standard engagement   infantry couldn’t assault bunkers frontally without accepting catastrophic casualties   Brenner had seen it before the British would call for artillery   his position would survive the bombardment due to the reinforced construction

and the engagement would  stall until one side withdrew   or reinforced then Brenner saw something that made him pause   a British tank was moving forward but it looked wrong where the main gun should be   there was only a short stubby tube barely longer than the turret itself   so wide it looked like someone had welded a metal cylinder to the tank as a joke   the proportions were absurd normal tanks had long   elegant gun barrels that  extended well beyond the hull   this thing looked like  someone had cut the gun off

and replaced it with industrial piping what is that one of Brenner’s gunners asked   squinting through the firing slit a dustbin the others laughed   a dustbin that’s exactly what it looked like some British engineer had apparently   mounted a trash can on a tank turret the laughter continued as the tank stopped   approximately 80 meters from their position close enough that Brenner could   see the peculiar weapon clearly the turret rotated   aligning the stubby tube directly at their bunker there was a sound not the sharp

crack of a tank gun but a deep hollow thump   like someone hitting an enormous drum Brenner saw something arc through the air   it moved slowly enough to track visually tumbling awkwardly clearly visible as a large   cylindrical object that looked exactly like what   his gunner had called it a flying dustbin   the object struck the bunker’s front wall just left of the main firing slit   the explosion wasn’t like artillery or tank fire   it was deeper heavier the blast wave   travelling through the concrete structure itself rather than just impacting the surface

the entire front wall of  the bunker collapsed inward   reinforced concrete that had been one meter thick reduced to rubble and dust   in an instant the firing slit disappeared the machine gun position disintegrated   Brenner was thrown backward by the shockwave his ears ringing temporarily blinded   by dust and debris when he could see again   most of his position no longer existed the front wall was gone   the roof was partially collapsed three of his men were buried in rubble   the ones who’d been laughing seconds earlier were dead or dying

the bunker that had protected them for 18 months had been destroyed by a single shot   from a weapon that looked like a crude joke Brenner crawled out through the wreckage   surrendering to British infantry who approached carefully weapons ready   one British soldier gestured  at the destroyed bunker   and said something Brenner didn’t understand but the meaning was clear enough   from the man’s expression that’s what happens when you stay inside   the tank that had destroyed  his position sat motionless

80 meters away its stubby weapon already traversing toward the next bunker   Brenner had thought it looked ridiculous he understood now   that it was the most terrifying thing he’d seen in the entire war   a weapon designed specifically  to erase fortifications   and one that worked exactly as intended the fortress problem   Britain’s decision to develop specialized bunker busting weapons   emerged from tactical reality that became apparent during operations   from North Africa through Italy and into north western Europe

German defensive doctrine centred on fortified positions   that conventional weapons couldn’t eliminate efficiently   German fortifications ranged from hastily constructed fieldworks   to sophisticated concrete bunkers with walls exceeding 1 meter thickness   reinforced with steel bars and designed to withstand direct hits   from artillery shells The Atlantic Wall   represented the culmination of this approach thousands of fortified positions   covering potential invasion beaches each one positioned to provide mutual support

and create overlapping fields of fire that would devastate any assault force   attempting to advance British tank guns   even the relatively powerful 17 pounder weapons mounted on Sherman fireflies   were designed primarily for  engaging armoured vehicles   against concrete fortifications they achieved minimal effect   a 17 pound armour piercing shell would penetrate tank armour efficiently   but would merely chip concrete  when fired at bunkers   high explosive shells were more effective but still required multiple hits

to achieve significant damage and German bunkers   were specifically designed  to survive such bombardment   artillery could destroy fortifications given sufficient time and ammunition expenditure   a sustained barrage from field artillery would eventually reduce most bunkers to rubble   but artillery required extensive preparation consumed enormous quantities of ammunition   and wasn’t always available when assault forces needed immediate support   infantry attacking fortified positions couldn’t wait hours for artillery preparation

they needed bunkers eliminated immediately during the assault itself   at the moment when delay meant casualties air strikes were similarly problematic   bombing fortified positions achieved results when bombers could deliver ordinance accurately   but close air support was  unreliable due to weather   coordination difficulties and the risk of hitting friendly forces   Infantry couldn’t depend on  air support being available   at the critical moment when they needed specific bunkers destroyed   to continue their advance the tactical problem was straightforward

assault forces needed weapon that could destroy   fortified positions immediately without waiting for artillery preparation   or air support using platform that could accompany infantry   during the assault and  eliminate bunkers on demand   the weapon needed to be mobile protected against small arms fire   and capable of delivering explosive power sufficient to collapse reinforced   concrete structures the solution Britain developed   was the Avre armoured vehicle Royal Engineers mounting the petard spigot mortar

a weapon so unconventional that both British troops and German defenders   initially questioned whether it was serious military equipment   or some kind of improvised field modification the spigot mortar solution   the petard represented fundamentally different   approach to bunker destruction compared to conventional weapons   rather than attempting to  penetrate fortifications   through kinetic energy or shaped charges the petard delivered massive   explosive charges that destroyed structures through blast effect

the weapon was technically a spigot mortar a launching system   where the projectile contained  the propellant charge   and fired from a fixed rod rather than from inside a gun barrel   this design allowed for projectiles far larger than conventional guns could fire   since the projectile diameter wasn’t constrained by barrel dimensions   the petards projectile was a  cylinder 26 cm in diameter   containing 18 kg of high explosive roughly equivalent to a large artillery shell   or naval depth charge the weapon replaced

the main gun on Churchill tanks that were converted to Avre configuration   where a normal tank turret mounted a gun barrel two or three meters long   the petard installation was barely one meter a stubby tube   that protruded just beyond the turret face the visual effect   was exactly what German observers noted it looked like someone had replaced   a proper tank gun with industrial equipment   that didn’t belong on a combat vehicle the firing mechanism was simple and robust   the projectile officially designated the 40 lb Flying Dustbin by troops

who appreciated accurate nomenclature was loaded onto the spigot rod inside   the mortar tube firing   ignited the propellant charge  in the projectile’s base   launching the bomb with distinctive deep thump that was immediately   recognizable to anyone who’d heard it before   the projectile arced through the air slowly enough to be visible in flight   and detonated on impact with the target the effective range was   approximately 80 to 100 meters beyond that distance accuracy degraded rapidly   and the arcing trajectory made hitting specific targets difficult

this limitation was deliberate the weapon was designed for Point   Blank assault work where the AVRE   would drive directly toward fortified positions and engage them at ranges   where missing was nearly impossible the reload process   was the system’s most distinctive feature unlike conventional tank guns   that loaded from inside the turret the petard required external reload   a crew member had to open the turret hatch lean out of the tank while exposed to enemy fire   manually load the massive cylindrical projectile onto the spigot rod

and close the hatch before  the weapon could fire again   the entire process required  approximately two minutes   under combat conditions during which time the tank was vulnerable   and the crew member conducting the reload was completely exposed   British engineers recognized this vulnerability   but concluded it was acceptable given the weapon’s tactical role   AVR’s weren’t meant to engage in sustained combat they advanced with assault forces   destroyed specific high value targets like bunkers or fortified buildings

and then withdrew while conventional   tanks provided ongoing fire support the slow reload rate was less important   than the weapon’s ability to eliminate fortifications   that nothing else could destroy efficiently the mathematics of demolition   the petard’s effectiveness against fortifications came from delivering concentrated explosive force   against structures that were  strong in some directions   but relatively weak in others reinforced concrete fortifications   were designed to resist  penetration from the front

the direction from which enemy fire would typically arrive   German bunkers had frontal armour that could withstand direct hits   from artillery shells with walls 1 meter thick   and reinforced with steel bars embedded in the concrete matrix   this construction made them nearly immune to conventional tank guns   and difficult to destroy even with sustained artillery bombardment   but concrete structures were vulnerable to blast overpressure   that travelled through the material itself rather than attempting to penetrate from outside

when the petards 18 kilogram warhead   detonated against a bunker wall the explosion created shockwave   that propagated through the concrete causing internal fracturing and   structural failure the reinforcement bars   that strengthened the  concrete against penetration   couldn’t prevent this blast effect the entire wall would fail   as the concrete fractured under forces that exceeded its structural limits   the tactical advantage was overwhelming a single petard round could destroy bunkers   that would require dozens of conventional tank gun rounds

or sustained artillery bombardment to eliminate the efficiency calculation favoured the petard   decisively one a V R E   with approximately 30 flying dustbin rounds could destroy more fortifications   in an assault than an entire battery of field artillery   firing for hours the psychological effect was equally significant   German troops defending fortified positions understood that concrete walls   provided Protection against most weapons   bunkers were supposed to be safe places where defenders could fight from cover

protected against small arms resistant to artillery   the petard violated that Assumption completely when a flying dustbin hit a bunker   the structure simply ceased to exist walls collapsed roofs caved in   firing positions disintegrated defenders inside were buried in rubble   or killed by the blast wave traveling through the structure   German soldiers Learned that when AVR’s appeared remaining inside bunkers meant certain death   the fortifications that were  supposed to protect them   became traps that ensured they’d be killed when the petard rounds arrived

this realization fundamentally changed defensive tactics   troops began abandoning  bunkers when AVR’s approached   preferring to take their chances in the open rather than waiting to be buried alive   when their position collapsed around them the Normandy Proving Ground   d day operations on June 6th, 1944 provided the first large scale combat   test of AVRE capabilities   and the results validated the concept decisively   the Atlantic wall fortifications covering Normandy beaches   represented exactly the  kind of defensive positions

the Avre had been designed to defeat concrete bunkers with interlocking fields of fire   positioned to devastate landing forces protected by minefields and obstacles   that would channel attackers into predetermined killing zones   German commanders were confident these defenses would inflict catastrophic   casualties on any invasion force buying time for reinforcements to arrive   and potentially throwing the invasion back into the sea   British assault forces included  specialized armor units   the 79th Armored Divisions funnies that deployed various modified tanks

for specific tactical roles among these were avrees   equipped with petard mortars task with eliminating fortified positions   that would otherwise halt  the advance of the beaches   the AVR’s went ashore in the first waves advancing with infantry toward   the fortified positions covering the beach exits   German defenders opened fire from bunkers that had been positioned   to provide interlocking coverage creating fields of fire   that conventional assault  methods couldn’t penetrate   without massive casualties the AVR’s identified priority targets

bunkers blocking critical routes positions that threatened advancing infantry   fortifications that artillery couldn’t suppress effectively   at distances that ranged from 60 to 100 meters the avrees fired their petard mortars   the flying dustbins arced toward their targets with trajectories that were visible to   both attackers and defenders   tumbling through the air  before impacting bunker walls   with explosions that German troops later described as feeling like earthquakes   bunkers that had been designed to withstand prolonged bombardment collapsed from single hits

firing slits disappeared as walls fractured and caved inward   positions that would have  required extensive artillery   preparation or prolonged infantry assault were eliminated in seconds   the tactical impact was immediate and profound beach exits   that German defenders expected to hold for hours were cleared in minutes infantry   that would have been pinned down by bunker fire advanced   rapidly behind avrees that  eliminated strong points   systematically the Atlantic Wall fortifications   that were supposed to make invasion impossible proved vulnerable to weapons

that delivered blast effects conventional guns couldn’t match   one British after action report noted AVR’s proved invaluable   in reducing fortified positions bunkers that resisted conventional tank fire   and required extensive artillery preparation were destroyed with single petar rounds   the weapon’s psychological effect on enemy troops was substantial   defenders frequently abandoned positions when AVR’s approached   rather than waiting to be engaged recommend increased Avre allocation   for future assault operations German reports were more blunt

one regimental commander reported British engineer tanks   mounting large calibre demolition weapons destroyed our strongest positions   with single shots concrete fortifications   that were designed to withstand  sustained bombardment   collapsed instantly when struck by these weapons defensive positions became death traps   rather than Protection troops increasingly refused to remain in bunkers   when these tanks approached the German perspective   German forces developed  specific recognition for avari

threat and attempted various countermeasures none of which proved particularly effective   initial encounters generated reports that German intelligence analysts   found difficult to credit frontline units described British tanks   mounting unusual weapons that destroyed fortifications with single shots   but the descriptions seemed  exaggerated or confused   how could a tank mounted  weapon destroy reinforced   concrete bunkers more effectively than artillery the claims seemed implausible   until sufficient evidence accumulated that the reports were accurate

once German commanders recognized the Avari as distinct threat   they attempted to develop countermeasures the obvious approach was destroying AVR’s   before they could engage fortifications anti tank guns were positioned   to cover approaches to defensive positions with orders to prioritise any tanks   displaying the characteristic stubby mortar tube but AVR’s typically advanced with infantry   and supporting armour making it difficult to engage them selectively   destroying one AVRE often required exposing

anti tank positions to fire from multiple British tanks   resulting in losses that  German forces couldn’t sustain   some units attempted to  concentrate fire on avrees   during their vulnerable reload period when crew members were exposed outside the turret   this achieved occasional successes AVR’s were lost to small arms fire   or artillery during reload but didn’t significantly reduce   the vehicle’s effectiveness AVR crews Learned to conduct reloads behind cover   or while protected by smoke making them difficult targets even when exposed

German troops developed informal doctrine of evacuating bunkers when AVR’s appeared   orders typically specified that defenders should maintain positions   under normal circumstances but when British engineer tanks approached   troops were authorized to withdraw rather than remaining in fortifications   that would likely collapse on them this represented tacit admission   that fortified positions offered no Protection against petard rounds and that troop survival   depended on avoiding engagement rather than attempting to defend fixed positions

one German company commander reported remaining in concrete bunkers   when British demolition tanks approach is suicidal the weapons they employ   destroy our strongest positions instantly troops understand this   and increasingly refuse to remain in bunkers when these tanks are present   fortifications that were intended to protect our forces have become traps that ensure casualties   if occupied when attacked recommend withdrawal from fixed positions   when British engineer tanks are identified even though this violates defensive doctrine

the assessment represented   fundamental failure of German defensive strategy The Atlantic Wall and subsequent defensive lines   had been constructed around Assumption that fortifications would protect defenders   allow them to inflict disproportionate casualties on attackers   and enable outnumbered forces to hold positions against larger enemy formations   AVR’s violated every element of this calculation fortifications didn’t protect defenders   they created confined spaces where troops would be killed

when structures collapsed casualties were disproportionate   but in the wrong direction defenders died while attackers survived   small forces couldn’t hold positions against larger formations   when their fortifications could be systematically destroyed in seconds