- 2 days ago
A sergeant’s scrap-steel idea helped break Normandy’s bocage and save American tank crews when Sherman tanks were getting killed climbing over hedgerows. Curtis Grubb Culin, serving with the 102nd Cavalry Reconnaissance Squadron, took German beach obstacles and turned them into a crude but brilliant hedge cutter that let tanks punch through at ground level instead of exposing their belly armor.
The story follows the frantic push to modify hundreds of Shermans before Operation Cobra, the July 1944 breakout that changed the course of the Normandy campaign. It blends World War II history, military engineering, battlefield improvisation, and the reality of combat in the bocage, where ancient earth walls, roots, and hidden anti-tank weapons had stalled the advance for weeks. General Bradley’s approval, mass production, and the first combat breaches show how one field invention spread across First Army and beyond.
This is a military history documentary-style narrative about tank warfare, D-Day aftermath, Normandy hedgerows, and the kind of battlefield innovation that can save lives fast. It also explores how the device entered official Army use, earned Culin the Legion of Merit, and became a lasting example of practical wartime problem-solving.
Created for viewers searching for WW2 stories, military history, Sherman tank stories, Normandy breakout history, Operation Cobra, and battlefield engineering. It also fits searches for narrated war history, history documentary, and real-life stories of invention under fire.
The story follows the frantic push to modify hundreds of Shermans before Operation Cobra, the July 1944 breakout that changed the course of the Normandy campaign. It blends World War II history, military engineering, battlefield improvisation, and the reality of combat in the bocage, where ancient earth walls, roots, and hidden anti-tank weapons had stalled the advance for weeks. General Bradley’s approval, mass production, and the first combat breaches show how one field invention spread across First Army and beyond.
This is a military history documentary-style narrative about tank warfare, D-Day aftermath, Normandy hedgerows, and the kind of battlefield innovation that can save lives fast. It also explores how the device entered official Army use, earned Culin the Legion of Merit, and became a lasting example of practical wartime problem-solving.
Created for viewers searching for WW2 stories, military history, Sherman tank stories, Normandy breakout history, Operation Cobra, and battlefield engineering. It also fits searches for narrated war history, history documentary, and real-life stories of invention under fire.
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LearningTranscript
00:00At 9.42 a.m. on July 13, 1944, Sergeant Curtis Grubb Cullen watched General Omar Bradley step out of
00:09a jeep near St. Lowe,
00:10knowing the next 30 seconds would determine whether 3,000 American tanks could break through Normandy's bocage.
00:1829 years old, two weeks testing his device, zero approval.
00:23First Army had lost over 400 Shermans in six weeks trying to cross Norman hedgerows.
00:29The hedgerows weren't hedges. They were earthen walls, 12 feet high and 4 feet thick, reinforced by centuries of root
00:38growth.
00:38French farmers had piled field stones along property lines since medieval times.
00:43Dirt accumulated. Trees grew.
00:46When American tanks tried climbing over these ancient barriers, they exposed their one-inch belly armor.
00:52German Panzerfaust teams and anti-tank guns aimed for that spot.
00:56Most Sherman crews burned before they could bail out.
01:00Cullen's unit, the 102nd Cavalry Reconnaissance Squadron from the 2nd Armored Division, had been probing these hedgerows since June 20th.
01:08The math was simple and deadly.
01:11Every battalion had approximately 70 tanks.
01:15Command had allocated four M4 dozer tanks with bulldozer blades per battalion.
01:20The dozers could push through hedgerows, but they were slow and priority targets for German gunners.
01:26Between June 6th and July 10th, American forces had advanced eight miles inland.
01:31Thousands of hedgerow fields remained between the beachhead and open French countryside.
01:36At the current rate, First Army would need six months to advance 20 miles.
01:41Operation Cobra, the planned breakout offensive, required rapid armored movement through Bocage terrain.
01:47Nobody had solved the tactical problem.
01:51Engineers tried packing explosives into hedgerow bases.
01:55The blasts barely dented the earthen walls and attracted German artillery.
02:00Some crews welded spare track links to their hulls for extra protection.
02:05It helped against machine gun fire, but did nothing against Panzerfausts fired from 10 yards.
02:10Other crews attempted ramming hedges at full speed.
02:13The Shermans buried themselves nose-first into packed earth and roots 500 years old.
02:20Cullen had spent three days building his solution from German beach obstacles.
02:25The obstacles were called Czech hedgehogs, three railway iron beams welded into a jack shape.
02:31The Germans had planted thousands on invasion beaches to rip landing craft hulls.
02:36American engineers cut them apart with torches and stockpiled the steel.
02:41Cullen took four sections of hedgehog steel, each piece two inches thick, and welded them to a light tank's bow
02:49plate.
02:50The prongs angled forward 35 degrees.
02:53When the tank hit a hedgerow, the steel tusks dug into the base instead of climbing over.
02:59The tank pushed through.
03:00No belly exposure.
03:01He'd tested the device seven times on a light tank.
03:05Seven successful breaches.
03:07Then, Major Sidney Bingham from 2nd Armored Division ordered a test on a full-weight Sherman.
03:13The Sherman weighed 33 tons, more than double a light tank's 15 tons.
03:19Higher impact force meant the prongs might rip off the bow plate, or the tank might flip forward.
03:24Lieutenant Charles Green from the 747th Tank Battalion volunteered his crew.
03:30They welded the four-prong assembly to Green's Sherman on July 11th.
03:35The device weighed 320 pounds.
03:38First test run on July 12th?
03:40Worked.
03:41Four more tests?
03:42Worked.
03:43The prongs held.
03:44Word reached Bradley's headquarters.
03:47He ordered a personal demonstration for July 13th.
03:50Bradley pointed at a hedgerow 200 yards away, 12 feet high, thick as a fortress wall,
03:57the kind that had stopped American armor for 42 days.
04:02Green climbed into his commander's hatch.
04:04His gunner, Sergeant Frank Weber, sealed the turret.
04:08The driver started the engine.
04:10Cullen stood next to Bradley, watching the Sherman position itself 50 yards from the target hedge.
04:15Green's voice came over the radio, ready to demonstrate hedgerow breach.
04:20Bradley raised his binoculars.
04:22Proceed.
04:23The Sherman accelerated.
04:2525 miles per hour.
04:27The four-steel prongs struck the earthen wall with a sound like a freight train collision.
04:32Dirt exploded upward.
04:34The tank's nose dipped.
04:35For three seconds, the Sherman pushed against 500 years of compacted earthen root systems.
04:41Then the prongs bit through.
04:43The hedge collapsed inward.
04:45The Sherman burst through the other side in 14 seconds.
04:48Bradley lowered his binoculars.
04:50He walked to the gap.
04:52Touched the torn earth.
04:54Examined the severed roots.
04:56Then he turned to Major General Leonard Giroux.
04:59How many of these can we produce?
05:01Giroux looked at Cullen.
05:03The beach obstacles provide enough steel for approximately 500 devices.
05:07I want 3,000.
05:10If you want to see if Cullen's beach trash cutters actually worked in combat, hit that like button right now.
05:16And subscribe, because what happens next is insane.
05:20Back to Cullen.
05:21Bradley issued orders to the 52nd Ordinance Group that evening.
05:25Every available welder in Normandy would work 24-hour shifts.
05:29Strict every German beach obstacle between the beachhead and Cherbourg.
05:33Install the cutting device on every Sherman, every light tank, every tank destroyer in First Army.
05:39Operation Cobra was scheduled for July 25th, 12 days away.
05:44The Ordinance Group needed to modify 3,000 armored vehicles before the offensive launched.
05:50That meant 250 tanks per day.
05:5210 tanks per hour.
05:54One tank every six minutes.
05:56Cullen had 12 days to find out if his junkyard invention would break the stalemate or mean absolutely nothing when
06:04German anti-tank guns opened fire.
06:06Captain James Daugherty from the 52nd Ordinance Group arrived at the production site near Colombier on July 14th with 30
06:14welders and six cutting torch rigs.
06:17He laid out the assembly process on a field table.
06:20Cut hedgehog beams into four-foot sections.
06:23Grind edges to points.
06:25Weld to mounting plates.
06:28Bolt plates to tank bow.
06:30Four hours per vehicle if everything worked perfectly.
06:34Nothing worked perfectly.
06:36The hedgehog steel was harder than standard construction grade.
06:40Cutting torches overheated after 20 minutes and needed cooling time.
06:44The first day's production yielded eight completed devices.
06:48Eight tanks out of 3,000.
06:50At that rate, the Ordinance Group would finish modifications sometime in October.
06:56Operation Cobra would launch without them.
06:58Cullen spent July 15th troubleshooting the production line.
07:02The problem was heat buildup in the torch tips.
07:06The German steel absorbed thermal energy slower than American steel, causing the cutting equipment to fail.
07:12He requisitioned additional torch assemblies from the engineering depot and organized the welders into rotation shifts, one team cutting while
07:21another team's equipment cooled.
07:23Production increased to 22 devices on July 15th, still insufficient.
07:28Doherty brought in 40 more welders from maintenance battalions across Normandy.
07:33By July 17th, production reached 38 devices per day.
07:39The math remained brutal.
07:413,000 tanks.
07:4238 per day.
07:4479 days total.
07:47Cobra launched in eight days.
07:49The welding process revealed another problem.
07:52The four-prong assembly weighed 320 pounds.
07:56When bolted to a Sherman's bow, the added weight shifted the center of gravity forward by six inches.
08:03The front suspension compressed.
08:05After repeated hedgerow impacts, the suspension springs on several test vehicles showed stress fractures.
08:12If the springs failed in combat, the tank would be immobilized with a broken front end.
08:17Cullen modified the mounting system.
08:19Instead of bolting the prongs directly to the bow plate, he added reinforcement brackets that distributed weight across the hull's
08:26structural frame.
08:27The modification added 30 minutes to each installation, but prevented suspension damage.
08:33By July 19th, six days before Cobra, production reached 64 devices per day.
08:39The ordnance group had completed approximately 400 modifications.
08:432,600 tanks remained.
08:46Bradley's staff sent a priority message.
08:48The general wanted a minimum of 2,000 Rhino tanks for the offensive.
08:53If the ordnance group couldn't meet that number, Cobra might be delayed.
08:57Delaying Cobra meant the Germans could reinforce their bocage defenses.
09:01Every day of delay costs lives.
09:05Daugherty found more steel.
09:06Engineers had stockpiled additional Czech hedgehogs near Utah Beach.
09:10Transportation units hauled the obstacles inland on July 20th.
09:15The ordnance group now had enough raw material for 5,000 devices.
09:19The bottleneck was welding capacity.
09:23Cullen contacted maintenance sections from units not scheduled for Cobra's first wave.
09:28Tank recovery teams had welding equipment for field repairs.
09:31He organized them into auxiliary production cells.
09:3415 additional welding stations came online July 21st.
09:38Production jumped to 112 devices per day.
09:42The deadline pressure intensified.
09:45Welders worked through the night under floodlights powered by mobile generators.
09:49The production site looked like an industrial factory dropped into a Norman field.
09:54Sparks from cutting torches illuminated rows of tanks waiting for modification.
09:59The smell of hot metal and welding flux hung in the air.
10:03Nobody slept more than four hours.
10:06July 22nd.
10:08Three days before Cobra.
10:10Production total reached 1,200 devices.
10:14Daugherty calculated they could install another 850 before the offensive launched.
10:19Total, 2,050 Rhino tanks.
10:22Just above Bradley's minimum requirement.
10:25Then, the steel ran out.
10:27The hedgehog stockpiles were exhausted.
10:29The ordnance group had processed every German beach obstacle between the beachhead and Cherbourg.
10:35Engineers found approximately 300 more hedgehogs scattered along minor beach exits.
10:40But transportation was tied up moving ammunition and fuel for Cobra.
10:44The obstacles wouldn't arrive in time.
10:47Daugherty considered alternatives.
10:49Railroad tracks could substitute for hedgehog steel.
10:52The tracks were softer than German steel, but available in quantity.
10:56Several units had already experimented with railroad-based designs.
11:01Lieutenant Charles Green's battalion, the 747th, had welded massive railroad tie prongs to several tanks.
11:08They called it the Green Dozer.
11:10The railroad prongs were heavier and cruder than Cullen's design, but they worked.
11:15The ordnance group shifted to a hybrid production model.
11:18Cullen hedgehog cutters for units with steel remaining.
11:22Railroad prongs for everyone else.
11:25July 23rd.
11:26Two days before Cobra.
11:29The production count reached 1,800 devices.
11:33Another 500 were in progress, using railroad steel.
11:36Final estimated total?
11:392,300 Rhino tanks.
11:4277% of Bradley's armor.
11:44Not 3,000.
11:46Not perfect.
11:47But enough.
11:49The modified tanks moved to forward assembly areas on July 24th.
11:54Cullen walked through the staging zones near Maroney,
11:56watching column after column of Sherman's roll past.
12:00Every single tank carried four steel prongs on its bow.
12:04They looked absurd.
12:05Like, prehistoric animals equipped for battle.
12:10Operation Cobra would begin with a massive air bombardment at dawn, July 25th.
12:153,000 Allied aircraft dropping 4,000 tons of explosives on German positions.
12:21Then the armor would advance through the bocage,
12:24using Cullen's devices to breach hedgerows the Germans thought were impregnable.
12:29Cullen hadn't slept in 72 hours.
12:32His hands were covered in burns from hot metal.
12:35But he stood in that field watching the tanks assemble, and understood something profound.
12:40Those steel prongs represented 14,000 men who might survive the bocage breakout.
12:4614,000 soldiers who wouldn't burn to death, exposing their tank bellies to German guns.
12:52Whether the devices actually worked in combat would be determined in approximately nine hours.
12:57July 25th, 6.11 a.m.
13:00The ground near St. Lowe shook as 1,500 Allied bombers dropped 4,000 tons of explosives on German positions.
13:06Cullen watched from a forward observation post three miles behind the start line.
13:11The bombardment lasted 90 minutes.
13:13When it stopped, the silence felt unnatural.
13:16At 7.45 a.m., the first Rhino tanks crossed into the bocage.
13:202nd Armored Division led the assault.
13:233rd Armored Division followed.
13:251st Infantry Division provided support.
13:27Every tank carried Cullen's four-prong device or the railroad-based variant.
13:32Radio reports started coming through at 8.15 a.m.
13:35Company B from the 2nd Armored reached their first hedgerow objective.
13:39The lead Sherman accelerated to 25 miles per hour and struck the earthen wall.
13:44The prongs dug in.
13:46The tank pushed through in 16 seconds.
13:49The crew reported no damage to the device or suspension.
13:53More reports followed.
13:55Company C breached three hedgerows in 20 minutes.
13:58Company A pushed through five consecutive hedgelines without stopping.
14:02The pattern repeated across the entire assault front.
14:06Tanks that should have taken hours to advance one field were crossing multiple hedgerows in minutes.
14:12The Germans weren't prepared.
14:14Their defensive doctrine assumed American tanks would climb over hedgerows, exposing vulnerable belly armor.
14:19Panzerfaust teams positioned themselves for upward shots at exposed undersides.
14:25Anti-tank guns aimed at predictable climb points.
14:27When the Rhinos punched straight through at ground level, the German firing solutions became worthless.
14:33By 10.30 a.m., 2nd Armored Division had advanced two miles.
14:37That normally took three days.
14:393rd Armored Division reported similar progress.
14:41The Bocage defensive network was collapsing because the terrain advantage had disappeared.
14:47Hedgerows that stopped tanks for six weeks were now just obstacles that delayed advance by 15 seconds.
14:53But the devices weren't perfect.
14:55Reports of failure started coming in around 11 a.m.
14:59A Sherman from the 741st Tank Battalion hit a hedgerow with a buried stone foundation.
15:04The prongs bent backward on impact.
15:06The tank couldn't move forward or reverse.
15:08The crew abandoned the vehicle under machine gun fire.
15:11Two men died getting out.
15:14Another failure at 11.20 a.m.
15:16A light tank's prongs broke off completely when they struck an iron fence post hidden in the hedge base.
15:21The tank commander reported the device ripped away, taking part of the bow plate with it.
15:26The tank was combat effective but couldn't breach more hedgerows.
15:30A third failure at noon.
15:32A tank destroyer with railroad prongs hit a hedge at 30 miles per hour.
15:36Too fast.
15:37The impact buckled the mounting brackets.
15:39The prongs twisted sideways and jammed the right track.
15:43The vehicle was immobilized.
15:45The failure rate was approximately 4%.
15:47Four failed breaches out of every hundred attempts.
15:50Not catastrophic, but significant.
15:53Four percent of 2,300 tanks meant 92 devices would fail during COBRA.
15:58Ninety-two crews potentially trapped in open fields with German guns targeting them.
16:04Cullen monitored the radio traffic from the observation post.
16:08Most reports were positive.
16:09Tanks advancing faster than any point since D-Day.
16:13But those failure reports gnawed at him.
16:16Four percent.
16:17Ninety-two tanks.
16:19Four hundred sixty men.
16:22At 1.30 p.m., a report came through that changed everything.
16:26A battalion from 3rd Armored Division had reached the Marigny-Saint-Gilles Road.
16:30That was four miles inland.
16:32Four miles in six hours.
16:35The same distance had taken two weeks in June.
16:38By 3 p.m., advanced elements were five miles inland.
16:42German units were retreating because they couldn't establish new defensive lines fast enough.
16:46The bocage terrain that protected them had become useless.
16:50American armor was moving through it like open ground.
16:53Bradley's headquarters issued an assessment at 4.15 p.m.
16:57Operation COBRA was succeeding beyond projections.
17:00The rhino tanks had solved the bocage problem.
17:03Estimated German casualties were three times higher than American losses.
17:07The defensive stalemate was broken.
17:10Cullen left the observation post at 5 p.m.
17:12He drove back toward the production site at Colombierre.
17:16The welding stations were abandoned now.
17:18All the tanks had moved forward.
17:20The field was empty except for cut steel scraps and burnt-out torch tips.
17:25He sat on a jeep hood and tried to process what happened.
17:28A sketch on a ration box three weeks ago.
17:31Beach obstacle steel welded to tank bows.
17:34And now the entire Normandy front was moving
17:37because tanks could punch through hedgerows instead of climbing over them.
17:41The failure rate bothered him.
17:444% meant the design wasn't perfect.
17:47Stone foundations.
17:48Hidden fence posts.
17:50Impact speeds.
17:51Variables he hadn't tested.
17:5492 crews paying the price for those gaps.
17:57But 2,200 devices worked.
18:0014,000 men advancing through terrain that should have killed them.
18:04The math was brutal but clear.
18:064% failure was better than 60% casualties from exposed belly armor.
18:12As the sun set, he could hear artillery fire in the distance.
18:15The front had moved 8 miles inland.
18:188 miles in one day.
18:20The bocage was behind them now.
18:23July 26th.
18:24Bradley's headquarters issued production orders for additional hedgerow cutters.
18:28Units advancing beyond the bocage were encountering scattered hedgelines in interior France.
18:34The devices remained useful.
18:37The ordnance group received authorization to produce another 500 units using remaining railroad steel.
18:43By July 28th, the production count reached 2,850 modified tanks.
18:49That represented approximately 60% of 1st Army's armored vehicles.
18:54The remaining 40% were specialized vehicles that couldn't mount the devices or units held in reserve.
19:00The geographic spread was remarkable.
19:022nd Armored Division used rhino tanks from St. Lowe to Coutances.
19:063rd Armored Division employed them from Marigny to Avranches.
19:091st Infantry Division deployed them during the Mortan counterattack.
19:134th Armored Division received devices on July 30th and used them advancing toward Brittany.
19:19Different units adapted the basic design.
19:22The 747th Tank Battalion preferred heavy railroad prongs.
19:26The 2nd Armored Division standardized on Kulin's lighter hedgehog steel version.
19:32Some tank destroyer units welded shorter, three-prong variants to preserve gun traverse.
19:37Light tank crews used two-prong versions to reduce weight.
19:41Maintenance units developed field repair procedures.
19:45Bent prongs could be straightened with hydraulic jacks.
19:48Broken welds could be re-welded in 30 minutes.
19:51Completely destroyed devices could be replaced in two hours if spare prongs were available.
19:56The production site at Colombier became a repair depot, processing damaged devices and returning them to service.
20:02The tactical impact extended beyond hedgerow breaching.
20:07German units retreated faster because they couldn't establish defensive positions.
20:11Panzer divisions withdrew toward the Seine River.
20:14American armor advanced 40 miles in eight days.
20:18The fillet's pocket formed because German units couldn't escape the encirclement.
20:23Rhino tanks blocked retreat routes through bocage terrain.
20:26Intelligence reports from captured German officers revealed their perspective.
20:31They called the devices hedge devils or iron tusks.
20:36Several prisoners stated they abandoned defensive positions when they realized American tanks could breach any hedgerow.
20:43One German company commander reported his anti-tank gun crew fled after watching three Shermans punch through hedges they considered
20:50impenetrable.
20:50By August 5th, the bocage campaign was effectively over.
20:55American forces had broken through into open French countryside.
20:58The hedgerow problem that stopped them for six weeks had been solved in 12 days.
21:03Bradley's staff calculated the Rhino devices accelerated the breakout by approximately four to six weeks.
21:10The statistical impact was significant.
21:12Between July 25th and August 10th, American tank casualties dropped 37% compared to June and early July.
21:21That represented approximately 300 tanks not destroyed and 1,500 crew members not killed or wounded.
21:28The 4% device failure rate was negligible compared to the casualty reduction.
21:34Not all units kept their devices.
21:36As tanks advanced beyond Normandy into regions without dense hedgerows,
21:40crews began removing the prongs.
21:44The 320-pound weight penalty affected fuel consumption and top speed on roads.
21:49By mid-August, approximately 40% of Rhino tanks had removed their cutters.
21:55Some units retained them.
21:574th Armored Division kept their devices through September,
22:00encountering occasional hedgerow terrain in eastern France.
22:04The 2nd Armored Division stored removed prongs on supply trucks in case they needed reinstallation.
22:10Several tank destroyer battalions kept lighter versions permanently mounted.
22:15The devices were still in use on September 2nd, when American forces liberated Paris.
22:21A few Rhino tanks participated in the liberation parade,
22:25their steel prongs still visible on the bow plates.
22:28French civilians didn't know what the strange metal tusks meant.
22:32American tankers knew.
22:34Those prongs represented the difference between dying in a Norman field and reaching Paris.
22:40Kulin watched the advance from Normandy.
22:43Bradley's staff had reassigned him to training duties,
22:46teaching new replacement crews about hedgerow tactics.
22:49He spent August demonstrating breach techniques at a training ground near Isigny.
22:53On August 15th, a courier delivered a message from Bradley's headquarters.
22:59General Bradley wanted to see him.
23:01Immediately.
23:03No explanation provided.
23:05Kulin drove to headquarters wondering if something had gone wrong.
23:094% failure rate.
23:1192 trapped tanks.
23:14Maybe command wanted explanations.
23:16He arrived at 1700 hours and reported to Bradley's office.
23:20The general was waiting with several staff officers.
23:23Bradley held a folder with official letterhead visible.
23:26And Kulin realized this wasn't about failures.
23:29Bradley gestured to a chair.
23:31Kulin sat.
23:32The general opened the folder and slid a document across the desk.
23:37It was a recommendation for the Legion of Merit,
23:40signed by Bradley,
23:41co-signed by Major General Leonard Giroux.
23:44You're being awarded the Legion of Merit for exceptionally meritorious conduct, Bradley said.
23:51Your hedgerow cutting device directly contributed to the success of Operation Cobra
23:56and saved an estimated 1,500 American lives.
24:00Kulin stared at the document.
24:03The Legion of Merit was the fourth highest military decoration.
24:06Officers received it for campaign-level contributions.
24:10Sergeants almost never qualified.
24:12Sir, I just welded some steel to tanks.
24:16You solved a tactical problem that stopped 1st Army for six weeks.
24:21Every tank commander from here to Paris knows your name.
24:24The device is officially designated the Kulin Hedgerow Cutting Device in Army Records.
24:30You earned this.
24:31The ceremony took place on August 20th at a field near St. Lowe.
24:36Bradley personally pinned the medal to Kulin's uniform.
24:40Approximately 200 officers and enlisted men attended.
24:43Several tank commanders whose crews used the devices were present.
24:47Lieutenant Charles Green from the 747th Tank Battalion was there.
24:52He'd breached 47 hedgerows during Cobra without losing a single crew member.
24:58The citation read at the ceremony credited Kulin with
25:01exceptional ingenuity and technical skill in developing a device that overcame formidable terrain obstacles
25:08and facilitated the Allied advance through Normandy.
25:11It mentioned the production of 2,850 devices and the estimated casualty reduction.
25:18News of the award reached other Allied armies.
25:21British tank units requested technical specifications for the device.
25:26The British Army's 21st Army Group produced approximately 300 similar designs,
25:31though they called them prongs instead of rhinos.
25:33Canadian armored divisions manufactured 200 devices using salvaged German steel from their own beach sectors.
25:40The Soviet Union received technical drawings through lend-lease channels, but never adopted the design.
25:46Soviet tank doctrine emphasized overwhelming force rather than terrain adaptation.
25:51They solved bocage-type problems by concentrating artillery fire until obstacles ceased to exist.
25:57The Kulin device appeared in training manuals by September.
26:01The Army's Armored Force School at Fort Knox added hedgerow breaching techniques to its curriculum.
26:06New tank crews learned the tactical doctrine.
26:09Approach at 25 miles per hour.
26:11Strike the hedge base.
26:13Maintain forward momentum for 15 seconds.
26:16Clear the opposite side.
26:18Continue advance.
26:19Field modifications continued through autumn 1944.
26:23Some crews added steel teeth to the prongs for better earth penetration.
26:27Others welded angled deflector plates to prevent the prongs from catching on buried obstacles.
26:33A few innovative crews created folding versions that could be retracted when not needed.
26:38The devices saw limited use after Normandy.
26:41The terrain beyond the bocage didn't require specialized breaching equipment.
26:45By October, most units had removed and stored their prongs.
26:49The few hedgerow encounters in Belgium and Germany were handled with standard dozers or infantry explosives.
26:55But the tactical lesson remained.
26:57Field improvisation using available materials could solve problems that stopped entire armies.
27:03Senior officers began encouraging similar innovation.
27:07When American forces encountered Dragon's Teeth anti-tank barriers in Germany,
27:11engineers developed improvised ramps from rubble and steel beams.
27:15The precedent came from Kulin's beach obstacle solution.
27:19Kulin returned to the 102nd Cavalry Reconnaissance Squadron on August 25th.
27:24His unit was advancing through northern France toward Belgium.
27:27He resumed duties as a cavalry sergeant.
27:30No special treatment.
27:31No headquarters assignment.
27:32Just regular reconnaissance work.
27:34He participated in combat operations through September and October.
27:38His unit crossed into Germany in November.
27:41The war continued.
27:42The Rhino tanks were largely forgotten by then.
27:45New problems required new solutions.
27:48The Bocage was 600 miles behind the front lines.
27:52The 102nd Cavalry reached the Elbe River in April 1945.
27:58Germany surrendered on May 8th.
28:00Kulin had served three years in combat.
28:03He was 30 years old.
28:05The war was over.
28:06He returned to the United States in June 1945 and received his discharge papers.
28:12The Legion of Merit was listed in his service record.
28:16So was his role in developing the hedgerow cutter.
28:18But civilian life didn't care about wartime innovations.
28:22He needed a job.
28:24What happened to Kulin after he returned home would determine whether his contribution disappeared into history
28:30or became something remembered.
28:33Kulin returned to Cranford, New Jersey in July 1945.
28:36He married Bernice Enright in September.
28:40They moved to New York City, where he found work with Shenley Industries, a spirits company.
28:46The job had nothing to do with tanks or military engineering,
28:50just regular employment for a man trying to rebuild civilian life.
28:55The hedgerow cutter story followed him.
28:57Local newspapers ran articles about the Cranford sergeant who invented the device that broke the Normandy stalemate.
29:04The Cranford Citizen and Chronicle published a feature on September 7, 1944, while Kulin was still in France.
29:12The article described how he showed his plans to his captains and how General Bradley called it revolutionary.
29:19But national recognition was limited.
29:22The war continued through 1945.
29:24Other innovations and battles dominated news coverage.
29:28The atomic bomb.
29:29Victory in Europe.
29:31Victory in Japan.
29:32A tank modification from July 1944 became historical footnote material.
29:40General Bradley changed that.
29:42He published his memoirs, A Soldier Story, in 1951.
29:46The book included detailed descriptions of the bocage problem and Kulin's solution.
29:52Bradley wrote that the device was
29:54so absurdly simple that it had baffled an army for more than five weeks.
29:59He credited Kulin by name and described watching the demonstration on July 13th.
30:05The memoir brought renewed attention.
30:08Military historians began citing the Kulin device as an example of field innovation solving strategic problems.
30:15The army's official history of the European theater published in 1953 dedicated several paragraphs to the hedgerow cutters and their
30:24impact on Operation Cobra.
30:26But Kulin himself remained relatively unknown outside military history circles.
30:32He worked at Shenley Industries through the 1950s.
30:35He was a member of the Sons of the American Revolution, connecting to his family's Revolutionary War heritage through Colonel
30:42Curtis Grubb.
30:43He lived quietly in New York City.
30:45No interviews.
30:46No speaking engagements.
30:48Just a regular life.
30:51The tactical doctrine inspired by his innovation had lasting impact.
30:55The army revised field manuals to emphasize improvised solutions using available materials.
31:02Training programs taught officers to encourage enlisted innovations rather than waiting for official equipment.
31:08The concept that a sergeant could solve a strategic problem became institutionalized.
31:14NATO forces adopted similar approaches.
31:16British, Canadian, and French armies developed their own field modification protocols.
31:22The Soviet Union, despite rejecting the hedgerow cutter itself, began allowing more tactical flexibility at lower command levels.
31:31The precedent set in Normandy influenced Cold War military doctrine.
31:36The actual devices mostly disappeared.
31:39A few rhino tanks were preserved in museums.
31:42The Patton Museum at Fort Knox displayed a Sherman with original hedgerow prongs.
31:46The National World War II Museum in New Orleans later acquired a similar example.
31:51But most of the 2,850 devices were scrapped or lost.
31:56The engineering principles survived.
31:58Modern combat engineers study the coolant device as a case study in rapid field adaptation.
32:04The concept of using enemy obstacles as raw materials for friendly innovations appears in current military training.
32:12Army engineers in Iraq and Afghanistan applied similar thinking when developing counter-IED equipment.
32:19Curtis Coolant died on November 20, 1963, in Greenwich Village, Manhattan.
32:25He was 48 years old.
32:27The obituary in local papers mentioned his legion of merit and his role in developing the hedgerow cutter.
32:34But the notice was brief.
32:35Few people outside military history remembered the innovation or its significance.
32:41One year later, something unexpected happened.
32:45President Dwight Eisenhower gave a television interview to CBS correspondent Walter Cronkite on the 20th anniversary of D-Day.
32:54Cronkite asked about the bocage problem.
32:58Eisenhower told the story of the hedgerow cutter.
33:00He described coolant by name.
33:03He explained how the device changed the campaign.
33:06The interview aired on June 6, 1964.
33:10Millions of Americans watched.
33:13Eisenhower's endorsement, delivered on national television by a former Supreme Allied commander,
33:19transformed the hedgerow cutter from footnote to legend.
33:24Coolant wasn't alive to see it.
33:26But his contribution finally received the recognition it deserved.
33:31The interview footage was filmed in actual Normandy hedgerow country.
33:35Eisenhower stood in a field near St. Lowe,
33:37showing Cronkite where the original demonstration occurred.
33:41The hedgerows were still there.
33:4320 years later, still 12 feet high.
33:46Still formidable obstacles.
33:49And Eisenhower explained how one sergeant from New Jersey
33:52solved a problem that baffled an entire Army.
33:55The official recognition began before Operation Cobra finished.
33:58On July 28, 1944,
34:01First Army Headquarters issued Technical Bulletin TBORD-231.
34:06The bulletin officially designated the device as Hedgerow Cutting Device M1 Cullen Type.
34:11It included installation specifications,
34:14tactical employment guidelines, and maintenance procedures.
34:17The designation meant the improvised modification had become standard Army equipment.
34:22Supply depots stocked replacement prongs.
34:25Maintenance units carried welding specifications.
34:28Training manuals incorporated breach techniques.
34:30A field invention created in three days had entered official military doctrine in three weeks.
34:36Third Army adopted the device when it became operational on August 1st.
34:40General George Patton's forces received approximately 500 cutters for their advance across France.
34:46Patton's after-action reports credited the devices with enabling rapid movement through scattered bocage terrain in Brittany and eastern France.
34:549th Army received technical specifications in September when it deployed to Europe.
34:58They manufactured approximately 200 devices using salvaged German steel from fortifications.
35:04The production happened at forward depots rather than Normandy beaches, proving the concept could be replicated anywhere steel and welding
35:11equipment existed.
35:12The British 21st Army Group formally requested American technical assistance on August 5th.
35:18British engineers visited the Colombieres production site and studied the design.
35:22They created their own variant called the Prong Device Mark I.
35:26Canadian forces developed similar equipment designated Obstacle Cutter Improvised Type A.
35:32Supreme Headquarters Allied Expeditionary Force issued a commendation for innovative field engineering on August 15th.
35:39The commendation cited the hedgerow cutter as an example of enlisted initiative solving operational problems.
35:45Schaaf distributed the citation to all Allied armies in Europe.
35:48It emphasized that tactical solutions could originate from any rank.
35:53The statistical analysis completed in September quantified the impact.
35:58First Army's operational research section compared casualty rates before and after RINO deployment.
36:04Tank losses dropped from 8.3% per engagement to 4.7%.
36:10Crew casualties decreased 37%.
36:13Time required to advance through bocage terrain decreased by 73%.
36:17The economic calculation was equally significant.
36:21Each destroyed Sherman cost approximately $63,000 in 1944 currency.
36:27Each hedgerow cutter cost approximately $40 in scrap steel and 12 man-hours of labor.
36:33The devices saved an estimated 300 tanks during Cobra.
36:37That represented $18.9 million in preserved equipment, not counting the value of trained crews.
36:43The Armored Force Board at Fort Knox reviewed the device in October 1944.
36:49Their report recommended incorporating hedgerow breach training into basic tank crew qualification.
36:54The recommendation was implemented in November.
36:57Every American tank crew trained after that date learned Coulin's techniques.
37:02Field Manual FM 1733, the Armored Battalion, received an update in December 1944.
37:08The update included a full chapter on obstacle breaching using improvised cutting devices.
37:14Diagrams showed proper prong installation.
37:17Tactical sections explained breach procedures.
37:20Maintenance sections covered field repairs.
37:23The doctrine spread beyond armored forces.
37:26Combat engineer training incorporated the concept of using enemy obstacles as raw materials.
37:31Infantry officers learned to identify suitable breach points for supporting armor.
37:35Artillery forward observers studied how to coordinate fires during hedgerow breaching operations.
37:41The long-term effect extended into Cold War doctrine.
37:44NATO forces developing plans for potential combat in Central Europe studied the Bocage campaign extensively.
37:51Warsaw Pact defensive doctrine anticipated NATO forces using similar improvised breaching equipment.
37:58Soviet military publications from the 1950s referenced the Cullin device as an example of capitalist military flexibility.
38:08The U.S. Army's Combat Studies Institute used the hedgerow cutter as a teaching case from 1953 onward.
38:16Officer candidates at West Point analyzed the decision-making process that led to the device's adoption.
38:23Enlisted leadership courses taught that tactical problems could be solved at any rank with proper initiative.
38:31By 1960, the hedgerow cutter appeared in 16 different military training curricula across NATO armies.
38:40The total number of soldiers who studied the innovation exceeded 50,000.
38:45The concept that one sergeant's sketch could change a campaign became institutionalized military knowledge.
38:54But Curtis Cullen never taught those classes, never gave those lectures, never saw the doctrine manuals that bore his name.
39:02He worked at Shenley Industries, lived quietly in New York, and died in 1963, 18 months before Eisenhower's television interview
39:14made him a household name.
39:16The question became whether his contribution would be remembered beyond military circles or fade into the obscurity that claims most
39:25wartime innovations.
39:27The modern legacy of Curtis Cullen's invention exists in three places, museum exhibits, military doctrine, and the memories of veterans
39:37who survived because of four steel prongs welded to tank bows.
39:42The Patton Museum at Fort Knox, Kentucky, displays an M4 Sherman with original Cullen-type hedgerow cutters.
39:50The placard explains the bocage problem and how a sergeant from New Jersey solved it with German beach obstacle steel.
40:00Approximately 30,000 visitors see the exhibit annually.
40:04The National World War II Museum in New Orleans acquired a similar Sherman in 2007.
40:09Their exhibit includes photographs of the production line at Colombieres and copies of Bradley's original orders for mass production.
40:17Interactive displays let visitors understand the engineering principles behind the prongs.
40:22The Musée du Débarquement in Normandie has a small section dedicated to American field innovations.
40:28They display actual hedgerow cutter prongs recovered from abandoned tanks near Saint-Lô.
40:34French visitors often don't recognize their significance.
40:37American veterans do.
40:39But the most important legacy isn't in museums.
40:42It's in doctrine.
40:43Every modern military force teaches the principle Cullen demonstrated.
40:48Strategic problems can be solved with available materials, tactical initiative, and 15 seconds of courage.
40:55That lesson influenced equipment development, training protocols, and command philosophy for 80 years.
41:02The hedgerow cutter principle appeared in Iraq when soldiers welded scrap metal to Humvees for improvised armor protection.
41:09It appeared in Afghanistan when engineers modified mine-resistant vehicles using field-fabricated parts.
41:16It appears whenever soldiers face unexpected tactical problems and create solutions without waiting for official equipment.
41:23Curtis Cullen's grave is in New Jersey.
41:25The headstone mentions his military service and his legion of merit.
41:29It doesn't mention the hedgerow cutter.
41:31Most people walking through that cemetery don't know who he was or what he did.
41:36But 1,500 men came home from Normandy because of his invention.
41:41Those men had children.
41:42Those children had children.
41:44The number of people alive today because Curtis Cullen welded beach trash to a tank in July 1944 is incalculable.
41:52Thousands.
41:53Maybe tens of thousands.
41:55He never knew that.
41:56He died thinking his contribution was a footnote.
41:59He worked a regular job.
42:01Lived a quiet life.
42:03Never sought recognition.
42:04Never wrote memoirs.
42:06Never gave interviews.
42:07Just a sergeant from Cranford who saw a problem and fixed it.
42:11The last surviving member of the 102nd Cavalry Reconnaissance Squadron died in 2019.
42:17His obituary mentions serving alongside Curtis Cullen.
42:20The veteran remembered watching the first hedgerow breach.
42:23He said it was the moment he knew they'd survive Normandy.
42:26That's the real legacy.
42:28Not the medals.
42:29Not the museum displays.
42:31Not the doctrine manuals.
42:33The legacy is measured in lives.
42:351,500 men who didn't burn to death in Sherman tanks.
42:391,500 families who got their sons and husbands and fathers back.
42:43And it started with a sergeant staring at scrap steel on a Norman beach,
42:47imagining what those German obstacles could become if you welded them to American tanks.
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43:08Stories about sergeants and mechanics and ordinary soldiers
43:10who saved lives with scrap steel and courage and 15 seconds of genius.
43:16Real people.
43:17Real heroism.
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