The basic background of these books is that the author's grandfather, Dieter Eckhertz, was a journalist for German news magazines such as Signal and Die Wehrmacht during World War II. In the spring of 1944, prior to D Day, he had toured sections of the so-called Atlantic Wall, including the Normandy area, and interviewed various soldiers from units in the area. Approximately 10 years later, he determined to track down these soldiers, or at least someone from each of the units, and re-interview them concerning their experiences during the D Day invasion. However, he ultimately did not publish these accounts (probably for reasons that you will realize as you read below). His grandson has organized the accounts and had them translated and published.
The first book are accounts from German soldiers that were in units actually stationed on or close to the beaches where the invasion forces landed. The second book contains accounts from troops that were in the area, but not actively involved in defending the beaches. The books are divided into "chapters," each of which are presented in an interview format: questions and answers. Given the nature of the book, these are not grand overviews of the German response to the invasion, but vignettes of the individual soldiers and their experiences.
Nevertheless, there is some information common to a majority of the accounts, some of which are to be expected and others which may be new to you.
First, the troops actually manning the defenses along the shoreline were, at best, third rate troops. They were part of what was termed the Static Infantry: generally soldiers that because of a medical or psychiatric condition were not suitable for regular infantry, but also including soldiers that had defected from the Soviets.
And that leads to the second point: all of the accounts from the soldiers manning the defenses were that there were a fair number of these foreign units, including many troops that were captured. However, these ex-Soviet troops were separated at the time of capture from the Germans and never seen again. Hearsay from one of the interviewees was that there were a number of Soviet officers that had gone in with the Allied troops; that the ex-Soviet prisoners were turned over to them and transported back to the Soviet Union where, undoubtedly, they were executed.
Third, the German troops were on very friendly terms with the French locals: buying food and spirits, becoming involved with local women, and so on. Only one of the interviewees had anything negative to say about the French, and that was a German military police officer who had been involved with investigating acts (crimes) committed by the French resistance (which he termed as terrorists). (Interestingly, this same individual had nothing good to say about British commandos, who he also likened to terrorists, especially their use of barbed-wire garrotes).
Fourth, none of the interviewees (even a couple with access to higher level intelligence and planning) expected a beach landing. Uniformly, they believed that the Allies would invade that summer, but that the Allies would have to capture a port (such as Calais), much as the British had attempted (but failed) to do a couple years previously. Thus, the ability to land tanks and set up a mobile port off the beaches probably had much to do with the apparent confusion among the German forces.
Fifth, the German troops were quite taken aback with incendiary weapons employed by the allies, such as flamethrowers (individual or mounted on tanks), napalm bombs, and white phosphorous shells and bombs. Reading through the accounts, these weapons appear to have been key to taking out bunkers on or near the beach; and several recounted incidents where whole columns of German (or other Axis troops) were wiped out with incendiary bombs from dive bombers.
Sixth, the interviewees were quite frank that they believed that Germany had created a "United Europe," and thought of themselves as defending not only Germany, but also France, from foreign aggression. Not only did the static infantry include non-German units, but many of the SS units in the area were non-German, including one described as being a Muslim unit (although it was not stated if they were Muslims from the Balkans or elsewhere). It is somewhat ironic that Hitler's dream of a United Europe under German domination has, for the most part, come to pass. I guess it could be said that Germany lost the war, but won the peace.
Seventh, the interviewees were surprised at the physical size of the American and Canadian troops. Better diet, I suppose.
Eighth, the interviewees seemed, for the most part, favorably disposed toward Americans prior to and after the invasion (although this may have been because of the influence America had over post-war Germany and desire to not bring down the ire of the Americans). The communists (i.e., the Soviets) were loathed.
Ninth, the Germans remarked at how stoic and professional the Allied troops were in their advance and fighting. Proof of their intense training and discipline.
Tenth, I noticed that all of the Germans that were captured were, if they were on their feet, immediately struck in the chest with a rifle butt and knocked to the ground. This came up so often that I decided it must have been part of the training of the Allied troops. The troops landing on the beaches (or a good number of them) must have been issued handcuffs, because the German soldiers that were captured in and around the landing area all reported being handcuffed before being sent back to the beach where the prisoners were being gathered.
Eleventh, it was interesting to me that the Germans that were in prisoner of war camps in Britain were paroled, even before the war was over, so that they could leave the camps and take jobs in the surrounding villages and towns. Only one of the soldiers interviewed had been shipped to a POW camp in the United States (Idaho, as it was). He indicated that they were never allowed to leave the camp. (However, that trooper was impressed by the quantity and quality of food the prisoners were given, even making a point of telling the interviewer that he was not describing meals for a special occasion or on Sundays, but everyday).
Twelfth, the use of bayonets figured prominently in the accounts of those soldiers that witnessed hand-to-hand fighting in and around the beach. I suspect that bayonets were used more during the war than most would believe. The paratroopers that had landed the night before apparently also made good use of their knives.
Thirteenth, the Germans lacked the aircraft to counter the Allies' air superiority. The Allies had air superiority from the get go. Also, close air support from dive bombers (British Hurricane and American Mustang fighters were often described) was decisive to the success of the invasion. Not only were many of the bunkers and fortification inland from the beaches destroyed by these aircraft, but the roving attacks made it impossible for the Germans to safely move troops during the daytime.
This raises another point that comes out from the interviews of the engineers working on the Atlantic Wall. The grand strategy was that although the Germans in and around the coast would blunt an invasion force, the Germans expected the Allies to penetrate inland a slight distance where other forces moving up would surround, contain, and destroy an invasion force. Thus, the reason for only using the Static Infantry at the beaches: they were only so-much cannon-fodder. Much of the Atlantic "Wall" was not a wall or fortifications, but shaping the landscape to channel and canalize invaders so that they could be easily destroyed by defending troops; essentially, that the landscape was crafted in such a way as to inevitably guide invaders into taking paths that were advantageous to the defending Germans. All of this came to naught because of the initial German belief that the Normandy landings were but a diversion, poor communication between German commanders and the front lines (aggravated by the sabotage carried out by the paratroopers), and the inability to quickly bring higher quality troops to bear because of the Allied dive bombers.
And this brings me to a final interesting matter that came up. The final interviewee of the second book was a German engineer that the interviewer believed to have been simply one of the units involved in the construction of the Atlantic Wall. Instead, he admitted to having been part of a secret weapon program that was developing a thermobaric weapon. At the time of the invasion, they had succeeded in making a weapon useful for the battlefield, but still dependent on favorable atmospheric conditions to not too quickly disperse the fuel cloud released by the weapon. His unit was tasked with destroying the entire port of Calais should the Allies gain a foothold. His unit was slow to be moved, and then the weapon was destroyed by a chance artillery barrage before it could be used. The engineer indicated that afterwards, the Germans improved the weapon so that the fuel cloud had better dwell time even in adverse conditions, and were working to make it deliverable by air (such as a bomber or a V-2 rocket). So, essentially, the Germans were on the verge of developing something to rival the destructive power of the first atomic bombs. However, as the situation deteriorated, the program was shut down and the scientists and technicians scattered to other assignments and locations.
In all, these were entertaining and interesting books and provide a viewpoint of the Normandy invasions that is absent from most accounts. The account of the thermobaric weapon was a surprise to me, and this may be the only extant account of such a weapon being developed by the Germans.
Update (5/12/2016): Typographical corrections.