Rhino tank The Rhino tank ( initially called " Rhinoceros " ) was the American nickname for Allied tank s fitted with " tusks " , or hedgerow cutting devices , during World War II . The British designation for the modifications was Prongs . In the summer of 1944 , during the Battle of Normandy , Allied forces – particularly the Americans – had bogged down fighting the Germans in the Normandy bocage . This landscape of thick banked hedges proved difficult for tanks to breach . In an effort to restore battlefield mobility , various devices were invented to allow tanks to navigate the terrain . Initially the devices were manufactured in Normandy , largely from German steel - beam beach defensive devices on an ad hoc basis . Manufacture was then shifted to the United Kingdom , and vehicles were modified before being shipped to France . While the devices have been credited with restoring battlefield mobility in the difficult terrain historians have questioned their overall usage and tactical significance . Background . Following the Normandy landings of June 1944 , as Allied forces pushed inland from the French coast , they found themselves operating within an area of Normandy ' s countryside known as the bocage . The actual bocage landscape extends further than the limited definition of " bocage normand " , that is to say , from the area directly west of Arromanches - les - Bains , including the entire Cotentin Peninsula , to the south of Brittany , Maine , and Vendée . In some areas , this terrain stretches for . This landscape contained large earth dikes averaging high that were covered with tangled hedge s , bushes , and trees that surrounded small raised irregular - sized fields , which were generally no more than across . The nature of the hedgerows — " sturdy embankments , half earth , half hedge " up to high with interlocking root systems — made excavating them extremely difficult , even with machinery . Narrow sunken tracks were the only pathways between these banks . Tank movement was severely restricted , preventing the Allied forces from bringing their vehicle superiority to bear , and making aerial observation with light aircraft like the Piper L - 4 Grasshopper and Auster AOP important in spotting German tank destroyers and anti - tank cannon emplacements concealed within the enclosed patches of land a distinct priority . The rolling landscape was also dotted with small rivers , woods , and fruit trees , along with scattered stone farmhouses and their outbuildings . Allied infantry , in particular the Americans , found themselves fighting from field to field against the Germans , who were positioned in prepared defensive positions housing machine gun and rifle emplacements . The Germans had in many places cut foxholes and other defensive structures directly into the hedgerows and embankments . These defensive positions limited the ability of the American forces to coordinate large - scale attacks or receive sufficient and accurate artillery support . Openings that did exist within the patchwork of hedges were already covered by German anti - tank weapons ; armor moving through these gaps attracted immediate defensive fire . Tank s were able to run over the banks — but in doing so they would expose their weak underside armor . Tactical developments throughout June involved combat engineer s blowing holes in the hedgerow walls for tanks to move through ; however , the explosions attracted German attention to the American positions . Invention . Prior to the launch of Operation Cobra ( an American offensive during the Normandy campaign ) , solutions were developed for how tanks could effectively support the offensive within this terrain . Bulldozers or tanks modified to carry a bulldozer blade were used to open gaps in hedgerows . Some hedgerows were so thick that engineers first had to blow a hole in the bank , which a bulldozer would later clear and widen . This time - consuming process slowed down the progress of the Allied offensive . Throughout July " innumerable " inventions were created by various American units to get tanks through the hedges quickly without exposing their weak underside armor . A hedgecutter developed by the 79th Infantry Division was in operation by 5 July , and a few days later , XIX Corps demonstrated a set of prongs that had been initially developed to create holes for the placement of explosives . These prongs were able to lift and remove a portion of the vegetation , enough so that the tank would be able to crash through to the other side . Units within V Corps also invented devices , which were dubbed ' brush cutters ' and ' greendozers ' . The invention of a hedge - breaching device is generally credited to Curtis G . Culin , a sergeant in the 2nd Armored Division ' s 102nd Cavalry Reconnaissance Squadron . However , military historian Max Hastings notes that Culin was inspired by " a Tennessee hillbilly named Roberts " , who during a discussion about how to overcome the bocage , said " Why don ' t we get some saw teeth and put them on the front of the tank and cut through these hedges ? " Rather than joining in the laughter that greeted this remark , Culin recognized the idea ' s potential . A prototype tusk - like assembly was created by welding steel scrap ( from a destroyed enemy roadblock ) to the front of a tank to create a hedge cutter . The teeth helped prevent the vulnerable underside of the tank from being exposed while it knocked a hole in the hedgerow wall . On 14 July , Lieutenant General Omar Bradley inspected the tank and " watched in awe as a hedgerow exploded . . . to make way for the Sherman bursting through " . According to Hastings , Culin , " an honest man " , attempted to give credit to Roberts , but this was forgotten in the publicity surrounding the invention . Hastings concludes : " [ Culin ] became a very American kind of national hero " . The American official campaign historian , Martin Blumenson , notes that Bradley , impressed , ordered the device be manufactured in quantity . Initially this was done using steel salvaged from the thousands of obstacles , such as Czech hedgehog s , that the Germans had placed on the French beaches during the construction of the Atlantic Wall . Bradley also dispatched Colonel John Medaris ( of the Ordnance Corps ) back to the United Kingdom to have tanks modified before being shipped to France , and arranged for additional arc welding equipment and crews to be transported to France by air . Around 500 of the assemblies , called the " Culin Rhino device " or " Culin hedgerow cutter " by the Americans , were manufactured . These devices were used to modify nearly three - quarters of the US 2nd Armored Division ' s M4 Sherman and Stuart tanks and M10 tank destroyer s in preparation for Operation Cobra . The British Royal Electrical and Mechanical Engineers ( REME ) referred to the devices as " Prongs " and produced 24 from ex - German beach defenses , but thereafter Prongs were produced in the United Kingdom . Six hundred Mark I Prongs were delivered by August , to be fitted to the Sherman V . A further 1 , 000 Mark II Prongs were produced , to be fitted on Shermans and the M10 , and 500 Mark III prongs were manufactured for the Cromwell tank . The Churchill tank s were not considered to need the Prong , but some were equipped with them nonetheless . Usage . War correspondent Chester Wilmot wrote after the war that the German defensive plan to halt any American breakout was to hold the front line " very lightly and to concentrate upon holding the road junctions for a depth of three or four miles behind the front " , with the intention of delaying any break - through by reducing the speed of the advance to the pace the infantry could manage . Once Operation Cobra was launched , Allied troops were able to bypass the German positions using the Rhino tanks , thereby allowing the advance to continue , leaving the strong points to be dealt with by infantry and engineers . Blumenson describes how during the launch of Operation Cobra , tanks with the 2nd Infantry Division , supported by artillery , advanced without infantry for twenty minutes , covering several hundred yards and knocking holes in hedgerows before returning to their starting position . The tanks and infantry then advanced rapidly together before the Germans were able to re - establish their defensive positions . During Operation Bluecoat ( a British offensive during the Normandy campaign ) , British Churchill tanks equipped with Prongs were able to traverse terrain considered impassable to tracked vehicles , taking the German defenders by surprise . Military historian Steven Zaloga claims that the devices " were not as widely used as the legend would suggest " , nor were they as effective as is often believed . But Max Hastings and Chester Wilmot credit the invention with restoring battlefield maneuverability to the Allied force . Martin Blumenson states that while the device restored mobility in hedgerow country , it " was of little tactical value in the breakout , except possibly as a morale factor to the troops , since the tanks advanced on the roads , not cross - country . " Notes . Footnotes Citations