In 1943 no principle existed within the U.S. Army for assaulting a heavily fortified coastline, and the only published advice in an U.S. Army Field Manual was that assaulting troops should avoid such defences and take them from the rear.
The Assault Training Centre’s assault doctrine had therefore begun from nothing. In May 1943 Thompson had called a month-long conference in London, seconding military experts from every service to thrash out a workable method of neutralising the German beach defences in western Europe. He called on speakers from experimental projects, collected vast amounts of data and photographs, and drew upon the combat experience of veterans of similar amphibious landings, including the raid on Dieppe.
Every aspect of the problem was considered, especially the terrain and topography to be encountered on the Normandy beaches selected for the American assault. This was probably the crucial element that dictated the whole doctrine, for unlike the British and Canadian assaults destined to cross sandy beaches onto undulating grasslands, the Americans would be faced with steep bluffs and only a few narrow valleys leading onto the plateau above.
While the British and Candians could therefore immediately use their tanks, the Americans had to seize the valleys leading off the beach first, leaving them no alternative but to attack the defences with infantry, and land their tanks once access off the beach had been secured.
Another factor that steered the conference to its conclusions was the lack of large landing craft, but a surplus of the humble LCVP. A thirty man capacity craft available in sufficient numbers, the LCVP proved to be the mainstay of the doctrine that was taking shape.
By the end of the month the doctrine was written together with a three week training schedule the conference concluded was necessary to adequately train soldiers in these new tactics.
A secret document of the time gives an appreciation of the problem and the American solution . . . “Modern fortified areas are characterized by a series of steel pillboxes, steel turrets, open emplacements, troop shelters, slit trenches and similar installations. Such defenses are commonly called Hedgehog.
The heart of the defensive system is the concrete and steel pillboxes. These are camouflaged, project only a small portion above the ground, and are so located as to provide interlocking zones of fire and mutual fire support. The entire area is surrounded by various anti-tank obstacles, ditches, tank traps, minefields, and from two to many bands of wire. The wire, minefields and normal avenues of approach for foot troops are liberally sewn with anti-personnel mines. The ground immediately before the weapon openings, or embrasures, in the pillboxes is levelled to provide long fields of fire. Where natural cover in the form of trees or underbrush is present, the trees and brush are cut down. Generally little, if any, natural cover for attacking troops exists.
The pillboxes have weapons that vary from machine guns to anti-tank guns up to light field artillery.
To successfully attack such a formidable area of new construction embodying the latest principles of modern tactics, infantry must be specifically trained, provided with additional weapons, and be backed up with a preponderance of artillery and direct fire weapons. In addition, air bombardment and ground support formations are extensively employed”.
The technique for direct assault of such hedgehog fortifications to be taught at the Assault Training Center followed a general plan . . . “ Infantry to be reorganized into assault sections; with flamethrowers and high explosive teams being the heart of the assault section. The troops advance under massed artillery and direct fire weapons preceded by an aerial bombardment, and covered by smoke. However, no reliance is placed upon actually reducing pillboxes by action other than direct assault.
The air and ground bombardments are relied upon to crater the area, spoiling the fields of fire and providing some cover, knock out the enemy artillery, destroy some of the open emplacements, and to cause the pillboxes to “button-up”, thereby allowing the infantry assault sections to advance and close with the enemy.
Upon the close approach of the assault troops, the artillery lifts to the rear areas, preventing the enemy bringing up reinforcements. The direct fire weapons, normally anti-tank guns, tanks, tank destroyers and infantry cannon continue to fire directly on the embrasures until their fire is masked by the infantry. At this point the assault troops cover the advance of the flamethrowers and demolition teams with rifle, anti-tank, and bazooka fire. Wire cutting teams cut or blow the wire using Bangalore torpedoes. When the flamethrower and demolition men are within 40 to 60 yards of the embrasures, the flamethrower is fired at the embrasure to permit the demolition men to place their high explosives within the embrasure. In short, the demolition team are the “ball carriers”. All other weapons and men are used to permit the demolition men to place their charges, thereby accomplishing the job of knocking out the pillbox.
Engineer troops closely follow the assault sections, and clear gaps thru the minefields, bridge anti-tank ditches and other tank obstacles to facilitate the forward movement of the track and wheeled vehicles. In most cases, Hedgehog are echeloned in depth.
In other words there are successive bands of these positions, several hundred yards apart in depth depending upon the terrain”.
Elements of the training programme were tested at Woolacombe by personnel of the 156th Infantry Regiment who were to be the instructors and guardians of the establishment. Only a few minor alterations were found necessary to individual lesson plans. The Assault Training Center was ready for their first trainees.
As the new doctrine drastically altered the conventional structure of an infantry division, the first problem to be encountered by the training staff was selling the idea to unit commanders. This was an issue that required diplomacy and rank to convince sceptical commanders that this was the way things had to be done, and the task fell to the Center’s Executive Officer, Lieutenant Colonel Lucius P. Chase.
He pointed out that the U.S. Army found itself presented with a unique problem they had not encountered before. They were to assault a fortified coast - not merely a defended coast such as encountered in Sicily or North Africa. And this could only be solved by a unique remedy, stressing there was only a limited objective for their assault Divisions - to establish a beachhead then defend it against counter-attack. Most were quick to realise these objectives were limited because of the devastating casualties their Divisions were expected to bear.
The re-arrangement of their units was justified further when it was pointed out that with amphibious assaults there had to be more flexibility and decentralization than in land doctrine because uncertainty of reconnaissance of targets rendered detailed assignment of tasks impossible. This was furthered by the very great risk of sinkings and faulty navigation, and these anticipated losses had to be distributed among landing craft of the assault waves.
It was spelt out that the assault had to be made by specially equipped and trained infantry sections as direct fire could not be depended upon to reduce pillboxes, and normal infantry weapons were powerless against concrete. Therefore beach defences were to be blown by hand placed charges. This was to be done by self-contained thirty-man "Assault Sections" that didn't exist in conventional infantry divisions, and were the reason for re-structuring
Training therefore had to be based upon several assumptions. Firstly that pillboxes and gun emplacements must be neutralised by flat trajectory, high velocity gunfire. Naval firepower was expected to provide this, but confidence in this eventuality gradually waned with training experience and alternative methods of delivering this initial barrage were explored and integrated into the American assault plan for D-Day. Tanks and artillery firing from landing craft as they approached the shore was one idea adopted, backed up by a small force of DD Tanks.
