Severloh's story is unique, largely because other German machine gunners were unwilling to exaggerate or lie about their experiences to the same extent. The landing on Omaha Beach was carried out by two divisions of the USA's V Corps; the 1st and 29th. Taken together, these divisions counted a total of 1,779 casualties to all causes on D-Day - 1,036 from the 1st and 743 from the 29th. When we count the V Corps troops that also landed on Omaha, such as the 5th Ranger Battalion, the number climbs to 2,220 killed, wounded or missing. This covers the entire frontage of Omaha Beach, and throughout the whole day, including after Severloh's position was neutralised. It also counts casualties caused by things other than small-arms fire, such as artillery fire and mines. If we take Severloh's claims at face value, then there must have been only ~220 casualties suffered along the whole rest of the beach, or caused by artillery fire, anti-tank guns, mines, drowning and the like. This does not seem credible, given the reports of heavy fighting along the beach, as well as frequent shellings by artillery and mortars. Given this, the only conclusion we can draw is that Severloh, at best, overestimated his claims.

Severloh was also not the only machine gunner at his strongpoint. Severloh was stationed at a position called Widerstandsnest 62 (Resistance Nest 62), or WN62. The main strength of WN62 was in its AT guns, with one modern 75mm gun and two old ex-Belgian 75mm guns, plus a 50mm gun. There were three mortars (2 50mm and one 81mm) positioned towards the rear, and three MGs. The MGs were distributed around the strongpoint, to ensure that a single shell could not knock all three of them out. Spreading them out also helped to reduce the number of locations where troops advancing up the beach could find cover - a location that was in cover from one MG might be vulnerable to another off on the flank. Severloh's gun was in a bunker, along with an artillery spotter. Another MG, likely an MG34, was in a 'Tobruk' position. This was a small, concrete one-man position, essentially a foxhole with better production values. The final MG was in a forward position, and one that was more rudimentary. The gun was a captured Polish weapon dating back to WWI, in a log and sandbag dugout.

There were positions like WN62 dotted along the Normandy coastline. There was a wide variety of strongpoints. Some were dug into already-existing buildings, such as WN37 at Le Hamel on Gold Beach, which reused the buildings of an old sanitorium. WN20, on Sword Beach, used sea-front houses to cover its bunkers. Others, like WN62 or WN5 on Utah Beach, were dug into the landscape, with completely new bunkers being constructed. The strongpoints, however, were not quite as well protected as the name suggests. Priority for construction had gone to the defences of the Pas de Calais, the part of the French coast that was closest to the UK, and therefore seen as a more likely target for an invasion. Many of the strongpoints along the Normandy coastline were still under construction; at least one of WN62's bunkers was incomplete on D-Day, and the casemates for the 75mm guns lacked armoured shutters. The bunkers were not armed with modern weapons, with many being armed with obsolete or captured weapons. The lack of supplies for construction and arming bunkers had two other effects. The gaps between bunkers were often too large. In a properly-planned defence system, each bunker or strongpoint would be able to provide its neighbours with covering fire and support; this was often not the case along the Normandy coast. There was also little depth to the defences; once the Allies had broken through the first line of strongpoints, there was little to hold them up behind the beaches. Sword Beach was the only one where there were effective defensive positions further inland. Here, WN17, a mile behind the beaches, would hold up the British 3rd Division's advance inland towards Caen until the evening. Not every beach had the advantages for the defenders that Omaha did. Omaha had steep heights behind the beaches, with only a few exits ('draws') which troops and vehicles could use to get off the beaches. This naturally funnelled the attackers towards certain points, allowing the defenders to concentrate, and gave the defenders advantageous firing positions. The terrain inland of the other beaches was generally flatter and more open. Finally, it should also be noted that the Allies held the advantage. They could pick and choose where to attack, choosing locations that were less well defended. They could interdict German reinforcements, and easily reinforce their troops on the beach. They had much more support and firepower at their disposal. These allowed them to exploit the failings of the German defences.

Beyond the inadequacies of the German defences, the Allied success on D-Day also depended on good planning and execution by Allied commanders and troops. The bombardment by both aircraft and ships was generally ineffective, but did suppress the German gunners, cut their lines of communication and distracted the heavy coastal batteries away from firing on the vulnerable transports. As the landings progressed, smaller ships like destroyers also provided more effective fire support to troops on the beach; gunfire from USN destroyers who had come in close to the beach helped to destroy or suppress a number of bunkers on Omaha and helped to break the deadlock. The use of amphibious DD tanks gave the troops who landed in the first waves armoured support. This provided heavy firepower for suppressing bunkers, cover against German fire, and a degree of mobility. Unfortunately, most of the DD tanks on Omaha and Utah were launched too far out from the beach. Many foundered in the high waves, and did not make it to the beach. This caused a significant part of the discrepancy in casualties between the American and British beaches. The arrival of tanks and other armoured vehicles in later waves would be a large part of the Allied breakthrough on Omaha. Finally, Allied infantrymen showed skill and courage in their abilities to advance under fire and knock out bunkers, using rifle grenades, hand-held anti-tank weapons, hand grenades and small-arms fire. While they did take casualties, the Allied infantry proved able to reduce and destroy German strongpoints relatively unsupported. The provision of tanks and naval gunfire reduced the casualties and made it easier to do, but some bunkers were knocked out by infantry alone. WN61, WN62's neighbour, was largely taken out by infantrymen from Company E and F, 116th Infantry Regiment.

why was Hein Severloh's story so unique? Why had other machine gunners not done the same and got a similar body count?

Combined Allied casualties for Operation Neptune were just under 4,500 killed in action, out of a total of around 10,000 total casualties spread across 5 landing zones. Due to the weather conditions, peculiarities of terrain and a general lack of the more specialised armour support, especially that seen in British and Canadian sectors, Omaha Beach where Severloh was stationed did have a disproportionate number of casualties, but not staggeringly so. Indeed, the US DoD calculated a total of around 2,400 killed, wounded and missing across all sectors at Omaha. Given that a significant number of casualties were caused by landing craft being swamped or drifting in bad weather and hitting beach defences - 22 LCVPs, 2 LCI(L)s and 4 LCTs were lost en route to Easy Red during the second wave - or by artillery, Severloh's account of killing 2,000 American soldiers is fanciful at best, and outright fantasy at worst.

Why was the whole beach line not dotted with a guy with a machine gun? It should not have been a big deal while having a huge effect.

The Normandy beaches were heavily fortified. However the MG42 can fire up to 1,300 rounds a minute and the sheer logistical requirements of lining the beach with machine gun emplacements when a few hardpoints could enfilade the entire beach were prohibitively expensive.

Thus, what made the Germans fail to succcessfully defend the beach?

A staggeringly degree of intelligence and logistical preparation went into Operation Overlord. Allied intelligence services mapped every inch of the landing zones and units were briefed and prepared for very specific objectives. The Americans at Omaha were scuppered largely by the weather, and the fact that so many landing craft were forced off-target, beached, swamped or otherwise prevented from reaching their designated targets. This meant that units that did reach the beach often found themselves nowhere near their practiced objectives, without their planned armour support or heavy equipment - or indeed without any equipment at all - or stranded on sandbard and forced to wade ashore through deep water to reach the shingle.

The other beaches were not so badly affected by the weather, and so units were typically able to arrive at their designated targets with their expected support and equipment. Here is some British Pathé footage of some of the specialist armoured units (in these cases based on the Churchill tank) designed to overcome beach obstacles. Note the 290mm spigot mortar on the AVRE, specifically designed to reduce German emplacements like Severloh's to rubble.