Built during World War II, The Atlantic Wall was considered the last major "Defensive Line" of the 20th century. It was a belt of fortifications built by Nazi Germany under Hitler's Führer Directive No. 40 to protect Fortress Europe from any seaborne invasion launched by the Allies from Great Britain. The wall was designed by engineer Fritz Toldt, who had also designed the defensive line on the French-German border.

So... assuming you were an Allied soldier:
The obstacles you would face coming to the beaches.

  1. The mines at sea
  2. Belgian Gates
  3. log ramps
  4. hedgehogs
  5. barbed wire
  6. The mines on the beaches (about 5.7 million - 6.5 million mines were laid)
  7. pillboxes and machine gun nests
  8. bunkers containing 66, 75, 88, 115, and 155mm gun emplacements. (about 14,000 bunkers were built)
  9. Rommel's asparagus (threat only to the airborne forces)

The Atlantic Wall was originally constructed between the Spring of 1942 until 1944 along the coasts of France and Belgium. The 3,000 miles of beachhead under the control of Field Marshall Karl Gerd von Rundstedt were woefully unprepared and inadequate to stand up to any invasion (although the Allies were not yet ready to invade with any sufficient force). This led to Hitler appointing Field Marshall Erwin Rommel to command Army Group B to strengthen the Atlantic Wall.

Hitler, Rundstedt (The commander of all Western German forces, Army Group B & G), and Rommel all had very different views about what the Wall represented and could do. To Hitler, the Wall was supposed to be the end all in defense again the Allies. Rundstedt believed that he should hold all his Panzer divisions in reserve until he could determine when and where the real invasion was coming from. When he had figured that out, he would send all his Panzers in a crushing, decisive blow. However, Rommel knew that the Wall would be unable to stop the Allies for very long. He believed that in order to stop the Allies they must be stopped at the beaches, and this meant that armored units and troops needed to be redirected quickly whenever an invasion occured so the forces woudl be driven off the beaches and back into the water. But this would prove difficult as Rommel was not allowed to move his troops without Hitler's orders (see below). Weaknesses of the Atlantic Wall on D-Day

Uncertainty
The Nazis had no clue as to where the Allies were going to land. Most German High Commanders (Including Hitler) thought that the attack would occur at the Pas-de-Calais, the shortest two points between Great Britain and France, and thus heavily fortified that area of France. Even as the Allies were attacking the beachheads of Normandy, most German commanders (those that were actually awake) thought that they were just a diversion to the actual invasion that was to happen at the Pas-de-Calais and possibly Norway.

No Air Support
German Luftwaffe at this time were nearly wiped out. Allied bombers and fighters in Operation Overlord bombings numbered around 11,000 (Only opposed by 400 Luftwaffe planes). They flew nearly 200,000 sorties dropping 195,000 bombs on German defenses including: Railroads, roads, air fields, radar stations, military bases, artillery batteries. Only one-third of the bombs dropped were near Normandy. Thus confusing the Germans further as to their real plan of attack.

Deception
The Germans were never certain where the attack would come from (see Uncertainty), however, three other covert operations confused the Germans into believing the landings at Normandy were not the real invasion.

  • Operation: Ultra - Allied operation that decoded the German Enigma code, thought to be uncrackable by the Germans.

  • Operation: Fortitude - This was the Allied operation called for the creation of a ficticious division, The 1st U.S. Army Group A.K.A. FUSAG). This ficticious army created heavy radio traffic that led the Germans to believe that the invasion would come from Norway. Prop makers were also brought in to make inflatable tanks, bombers, trucks, boats, ship and other vehicles. Other ficticious groups were also made which led the Germans to over-estimate the actual amount of Allied troops.

  • Operation: Double Cross System - Not really an operation, but by this time in the war, all German spies in Great Britain had been turned into double agents and were feeding the Germans with lots and lots of false information. They led the Germans to believe that the "real" invasion would be in Norway and the Pas-de-Calais and that Normandy would only be a decoy. Hitler was still waiting for the invasion of Norway well after the Allies had established beachheads on Normandy.

Lack of troops
Although the Wall was plenty defended, most of it was defended by the Ost (East) Battalion (static German defenses). Half of this battallion consisted of captured Russian and Polish troops. Not only were they ill-trained for defending the Wall, these troops would immediately surrender when they could. In fact, the only beach that met heavy resistance on D-Day, Omaha, was due to the fact that the 352nd German Division had recently replaced the troops there. Even so, the 352nd were so stretched that they could not put together a counter-attack to drive out the forces at Omaha.

The French Resistance
French resistance fighters helped Allied planners with knowledge on troop movement, gun emplacements and other construction projects that the Germans were planning. They also cut communication lines but their main accomplishment was the removal of axle grease from the trains carrying the Panzer division's tanks. They replaced the grease with a very harsh powder that broke the axles. This hindered the Panzer tanks for nearly two weeks after the invasion.

Ill-preparation
The German command structure was so unorganized that it was hard to figure out who your superior or command officers were and who held an equal rank to yours. The Anti-aircraft batteries were in territory that Rommel commanded. But in order to fire them, Rommel had to get permission from the Luftwaffe. The Panzer divisions (which had the Tiger-class tanks and very quick and armored motorcycles) that Rommel had wanted to use in his plans as the main counter-attack force were stationed at Rommel's bases, but they would only be allowed to move by Hitler's orders alone. Another thing hindering the Germans was that Rommel and Rundstedt were at odds with each other on what to do and since Rundstedt controlled all Western German forces and Rommel, only Army Group B, Rundstedt often objected to Rommel's demands. By the time any real organization could be done, it would have been too late.

No one at the reins
Hitler was asleep, Rommel was at his wife's birthday party and most other commanders were either (a) sleeping or (b) at a map exercise. Very few German commanders were available at the onset of the invasion.

Allied landing points
Utah Beach: U.S. 4th Division
Omaha Beach: U.S. 1st Division
Gold Beach: British 50th Division
Juno Beach: Canadian 3rd Division
Sword Beach: British 3rd Division


References
http://www.princeton.edu/~ferguson/adw/d-day.shtml
http://www.geocities.com/Athens/Olympus/6550/
http://www.militaryhistoryonline.com/wwii/dday/default.asp