Gen Fritz Bayerlein, commander, Kampfgruppe Panzer Lehr, provided some insight into what it was like to be on the receiving end of the Falaise air attack when he said, Traffic was in a terrific snarl in the village, moving north and east to get out of the Falaise–Argentan trap . . . Punctually at 0900 in the morning of the 13th came the fighter-bombers. They swept in very low over at least 250 motor transport, trucks, cannon, and nebelwerfer on the roads in and around the village and nearby fields and orchards. They hit a truck train of rocket ammunition right off the bat, and this 64 started exploding and throwing rockets in all directions. The streets of the town were so littered with the burning remains of trucks and equipment as to be impassable, yet the fighters kept on until it was practically dark, after which two-motor bombers came in and bombed intermittently at night.72
"[In World War I] aircraft became an offensive weapon of the first order, distinguished by their great speed, range, and effect on target. If their initial development experienced a check when hostilities came to an end in 1918, they had already shown their potential clear enough to those who were on the receiving end. ... We do not have to be out-and-out disciples of Douhet to be persuaded of the great significance of air forces for a future war and to go on from there to explore how success in the air could be exploited for ground warfare, which would in turn consolidate the aerial victory." -German Maj. Gen. Heinz Guderian, comment in 1937. Guderian became the father of the blitzkrieg used in World War II.
"[At the battle of Alam Halfa] nonstop and very heavy air attacks by the RAF, whose command of the air had been virtually complete, had pinned my army to the ground and rendered any smooth deployment or any advance by time schedule completely impossible. ... We had learned one important lesson during this operation, a lesson which was to affect all subsequent planning and, in fact, our entire future conduct of the war. This was that the possibilities of ground action, operational and tactical, become very limited if one's adversary commands the air with a powerful air force and can fly mass raids by heavy bomber formations unconcerned for their own safety. ... Anyone who has to fight, even with the most modern weapons, against an enemy in complete command of the air, fights like a savage against modern European troops, under the same handicaps and with the same chances of success. ... The fact of British air superiority threw to the winds all the tactical rules which we had hitherto applied with such success. In every battle to come, the strength of the AngloAmerican air force was to be the deciding factor." -World War II German Field Marshal Erwin Rommel, the "Desert Fox," in 1942.
"The enemy's air superiority has a very grave effect on our movements. There's simply no answer to it." -Rommel, when he was commander of German Army Group B at Normandy, days before he was strafed off the road by Spitfires and seriously injured.
"The long duration of the bombing, without any possibility for opposition, created depressions and a feeling of helplessness, weakness, and inferiority. Therefore the morale attitude of a great number of men grew so bad that they, feeling the uselessness of fighting, surrendered, deserted to the enemy, or escaped to the rear, as far as they survived the bombing. ... The shock effect was nearly as strong as the physical effect. ... For me, who, during this war, was in every theater committed at the points of the main efforts, this was the worst I ever saw. The well-dug-in infantry was smashed by the heavy bombs in their foxholes and dugouts or killed and buried by blast. The positions of infantry and artillery were blown up. The whole bombed area was transformed into fields covered with craters, in which no human being was alive. Tanks and guns were destroyed and overturned and could not be recovered, because all roads and passages were blocked." -German Lt. Gen. Fritz Bayerlein, in a postwar memoir on experiencing the Operation Cobra bombing at St. Lo, which set the stage for the Allied breakout across France.
The Ardennes battle drives home the lesson that a large-scale offensive by massed armor has no hope of success against an enemy who enjoys supreme command of the air." -German Maj. Gen. F.W. von Mellenthin, chief of staff of the Fifth Panzer Army at the Bulge, in a postwar memoir.
"[Field Marshal Gerd von Rundstedt, the commander of the attack at the Bulge, stated] that the main reason for the failure of the Ardennes offensive was his own lack of fighters and reconnaissance planes and the tremendous tactical airpower of the Allies." -Bradley in 1945.
GRIM REPLY General Fritz Bayerlein, commander of the Panzer Lehr Division, when ordered by Field Marshal Von Kluge to hold the line at all costs, replied angrily "Out in front every one is holding out. Every one. My grenadiers and my engineers and my tank crews, they are all holding their ground. Not a single man is leaving his post. They are lying silent in their foxholes, for they are all DEAD."
Don't take his words for true, though; the bombardment on Panzer Lehr of July 24th-25th, all weapons combined, cost the Germans about a third of the remains of the division.