Much is made of D-Day, but the Supremes would never have given it a go without a reasonable expectation that they could at least get ashore.
Staying ashore was another matter entirely.
Allied forces knew they would face an inevitable counterattack and unlike the decision to choose Normandy, they would have no say where and when the German hammer would fall.
Airborne forces ensured that troops punching through the coastal defenses could get inland and artillery support, often destroyers, such as the Emmons and the Doyle, lobbed 5-inch shells ashore, providing formidable firepower.
Delaying the counterattack was essential as the more divisions onshore and the farther inland they progressed lessened the chance of being pushed back into the Channel; a near pathological British fear after Dunkirk.
Since the fact of the impending invasion was hardly a secret, sowing doubt about the exact location was imperative and this the Allies did by creating a phony and virtual army headed by General Patton; the Germans took the bait as they could not conceive that the Allies would waste a command officer of Patton’s battlefield reputation.
The June 5/6 Airborne assault, as chaotic as it became, was quickly reported to OB West, the German command, but was viewed as a feint or diversion to draw off forces from the real invasion site; it was a very lucky break.
While the German troops manning the West Wall may have been of mixed quality, the OB West reserve was not, the 5th Panzer Army represented a significant threat if they were ordered into battle once the reality of the invasion was known.
5th Panzer was not employed on June 6th and it was another extraordinary bit of luck.
The reason can be largely chalked up to Hitler’s failure to delegate tactical decisions to his field commanders.
While it is true that von Rundstedt and Rommel differed on when and how to employ the reserve, it was up to Hitler to allow one or the other to have control; he did not, maintaining deployment authority himself.
Some British forces landing on the Sword beaches, such as at Hermanville-sur-Mer, met determined German forces which effectively stopped the objective of taking Caen immediately, the rapid advancement of 5th Panzer might well have been a decisive move.
Hitler’s micromanagement meant that the 5th Panzer Army sat idly by until June 8th when three divisions were moved to defend Caen, some nine miles inland from Sword, giving the Brits the opportunity to enlarge their footprint and prepare an offensive.
Had Rommel, known as both shrewd and aggressive, had his way, 5th Panzer may have been deployed instantly, driving the British off the beaches and potentially turning the left flank entirely.
As it was, the German counterattack was much delayed and finally occurred in the torturous and costly battle for Caen which lasted until August of 1944.
Though the British Second Army and Montgomery often come in for criticism over the delay in taking Caen, it is they who actually felt the German hammer fall and weathered the blows, with a little help from Hitler, of course.
Timing is everything.