It's the 70th anniversary of the Normandy landings.
It's all well and fine say, "Hey, kids! Let's invade France!" It's another thing entirely to do it, and then do it successfully.
It was foolish to try to base any troops on the coast. First, the massive facilities needed to house, feed, and train them would be clearly visible from the air, and German bombers would massacre the troops easily. Second, it would be a logistical nightmare to try to push food, clothing, equipment and supplies to such a small area. Third, any outbreak of disease would ravage the troops before the military medical divisions could react. Fourth, the social impact on local communities would be immense, and lead to a decline in political support for the prosecution of the war. Thus, any invasion force would need to be scattered throughout the country. This meant that in the one or two weeks prior to any invasion date, massive troops movements would begin to occur.
Moving troops was not a problem. Indeed, with so much train traffic at the time in Great Britain, no one would notice. But timing was critical: Any invasion date had to be set weeks in advance. And once in motion, the project couldn't be stopped easily. It would be logistically difficult to start moving large numbers of troops back to their quarters. It would be almost impossible to feed the troops, for one thing. Finding the fuel to move them back would be another. There was also the risk that troop transports might be bombed as well. And no military commander could ignore the devastating impact on troop morale: Soldiers who had steeled themselves to go into battle would lose their edge if they were made to wait, or (worse) sent back to the countryside to cool their heels.
Getting these troops over the ocean was another issue. About 6,900 ships would be needed. More than 1,200 warships would be needed to protect the landing and to provide fire support for the troops on the beachheads. The warships would not only seek to destroy shore defenses but also suppress enemy artillery fire and break up enemy troop concentrations as they assembled inland and moved toward the beaches. To move the troops, tanks, artillery, and equipment, more than 4,100 military and 850 civilian transport vessels would be needed. To provide fuel and ammunition for the warships and landing craft, communication, control, and command for the fleet, another 750 ancillary military warcraft were needed. Launching these ships at all once was not possible. Some ships would need to put to sea a day or two ahead of time.
Providing air cover was another problem. More than 12,000 aircraft would be needed. Bombers would be needed to bomb the entire French coast, including large numbers for Calais. Fighters would be needed to protect the bombers. Fighters would also be needed to fly patrol over Great Britain in order to fend off any counter-attack. And fighters would be needed to help close the English Channel and provide air cover for the invasion fleet. Finally, fighters and bombers would need to be kept in reserve to actually help support the invasion itself. And on top of all that, more than 1,000 transport aircraft would be needed to fly in paratroops and 3,900 light planes to tow glider troops into battle.
Another key to the invasion would be to deny the German Navy access to the English Channel. Cordoning off the English Channel might alert the Germans to the fact that invasion was imminent. But that was not as likely as it might seem. First, by mid-1944 most of Germany's battleships in the North Sea and North Atlantic had been damaged, its cruisers had green crews who were still in training, and the German Navy's fuel allocation had been cut by a third. The German fleet was largely staying at home. Even if it decided to sally out, the Royal Navy had mined the Kaiser Wilhelm Canal (now known as the Kiel Canal; the canal across the southern Danish peninsula which links the North Sea to the Baltic), and Allied warships could easily handle German surface naval forces. The Royal Navy had already created a U-boat cordon far west of Great Britain, and U-boats were rarely seen in the English Channel anyway. There were, however, substantial German surface forces south of the landing zones, in Brittany. So Allied navies laid extensive mine fields to keep surface ships away from the landing beaches. The goal was to keep the German Navy away from shore -- and its air cover -- so that Allied aircraft and warships could engage them and drive them off.
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Even if you get your ships, planes, and soldiers in one spot, aimed at one beach, then what?
When do you attack?
"When" often depended on what sort of defenses you had overcome.
Field Marshal Gerd von Rundstedt ("the Black Knight") and Field Marshal Erwin Rommel had been placed in command of the defense of Western Europe. But due to shortages in material and manpower, Atlantic Wall fortifications covered only the ports and beaches around them. Other beaches -- particularly those at Normandy -- were much less well-defended. Many of the coastal defense troops were men who had been too severely wounded to return to battle in the east; old men and teenage boys; or captured troops of Soviet client-states (such as Ukraine) who wanted to fight the Russians but not the Allies and whose loyalty to the Nazi Reich was questionable. In January and February 1944, Rommel began implementing training regimens for these troops. He also ordered the reinforcement of coastal defenses, including the laying of steel anti-tank and anti-ship obstacles under water or on beaches, the construction of concrete bunkers and pillboxes, and the flooding of low-lying areas so they could not be used for paratroop drops or glider attack. Punji sticks (known as "Rommel's asparagus") were set up in clearings and meadows to deter landings. But construction had not yet been completed in Normandy by June 1944 because Allied bombing of the railway system interfered with the movement of the materials and because the Germans were convinced that the Allied landings would take place at Calais.
The German High Command was also embroiled in a long-running and bitter debate over how best to defend Western Europe. Rommel argued that the Allies would possess air superiority. To counteract this advantage, armored divisions should be deployed close to beaches so that the Allies could not establish a beachhead. Von Rundstedt, however, argued that this spread Nazi tank formations too thinly. Armor should be concentrated in a central position around Paris and deployed in force against the main Allied beachhead once it had been identified. Adolf Hitler chose a compromise which placated neither general. Rommel would be given three armored divisions (far too few to provide the immediate counter-response his plans required), while Von Rundstedt would be given the remaining divisions. However, the divisions were to be placed near Rouen (closer to Calais), and removed from Von Rundstedt's command. Hitler alone would have the authority to order the units into combat. To help shore up his defenses, Rommel ordered his tank units as close to the beaches as possible and reinforced them with his reserves (leaving him nothing if the Allies broke through his lines).
Rommel's defensive measures meant that the Allies had to attack at high tide. This not only moved them closer to shore, but would allow most of their ships, amphibious tanks and armor, and landing craft to travel over the underwater and beach barriers. In fact, the best days would be a high tide during a full moon in the spring. In France, high tides are highest in the spring. And a full moon was needed to provide the most light for the nighttime attacks which would occur prior to the invasion.
The first high-tide-and-full-moon (a phrase which soon became associated with disaster) occurred on May 10, 1944. Allied troops began moving to the British coast, fuel reserves were created, ships readied, and the French Resistance was even alerted. But bad weather led to the cancellation of the invasion. This actually helped the Allied cause: The Germans had broken many of the code phrases and words used to alert the French Resistance to the invasion. When the next high-tide-and-full-moon occurred on June 5, German intelligence saw many of the same code words and phrases used again. But since no invasion had occurred in May, they dismissed them as an attempt at deception.
June 4, 5, or 6 would be the next date of the invasion.
Bad weather once again threatened to stall everything. The weather had been spectacularly good for two weeks, but then began to turn windy and wet. But once more Allied troops were already on the move, ships were ready, the Resistance was on alert. Another delay would be deadly to morale, and mean many more opportunities for the Germans to learn of the invasion plans and prepare. The Allied chiefs of staff met with General Dwight D. Eisenhower on June 5. American meteorologists forecast a brief improvement in the weather for 24 hours. British General Bernard Law Montgomery, British Admiral Bertram Ramsay, and American General Walter Bedell Smith wished to proceed, but British Air Chief Marshal Trafford Leigh-Mallory was doubtful. On the strength of the weather forecast, however, Eisenhower ordered the invasion to proceed.
Bad weather further weakened the German defenses. German intelligence believed that the weather meant no invasion would be possible for several days. German military leaders, therefore, allowed many troops to go on vacation or stand down from alert. A number of senior military commanders also took leave for the weekend. General Rommel returned to Germany to celebrate his wife's birthday. Many of the remaining military officers in France decided to participate in war games for the weekend, which took them away from their posts. Although most of these officers and soldiers had returned to their posts by Monday, the bad weather meant they did not feel the need to rush to return to alert status.
That Tuesday was June 6, 1944. D-Day.