...It was Rommel’s Seventh Army which held Normandy, with the Fifteenth responsible for the Pas de Calais, Belgium, and the Netherlands. The Germans had been at work on defences of the Atlantic wall since 1942. When Rommel took over as Supreme Commander in the West in November 1943, he pushed the work ahead as quickly as he could using half a million troops and conscript workers to strengthen defences.
Beaches were strewn with steel and concrete wrecking devices, with coastal roads being heavily mined and barred by fortifications and tank traps. Every accessible landing place was enfiladed by fire of hidden batteries and machine gun emplacements.
Rommel was convinced that the invasion would have to be stopped on the beaches, and that, for Allies and Germans alike, the first day would be the longest.
In due course the Chief of the Imperial General Staff, Field Marshall Alan Brooke, gave way to General Dwight Eisenhower who became the Allied Commander of the Invasion of Europe. Eisenhower’s base was Southwick House in Portsmouth; largely from here he ran the Supreme Headquarters for the Allied Expeditionary Force (SHAEF).
Eisenhower’s skill was in diplomacy, managing well the challenges of keeping the Allies together in the face of this monumental challenge. He had limited military experience and left much planning and administration in the hands of his Chief of Staff, Walter Bedell Smith, whom he promoted to Lieutenant General in January.

Of General Eisenhower, Brooke recorded in his diary on 15th May 1944: “...a champion of inter allied co-operation... a charming personality and good co-ordinator, but no real commander.”
Winston Churchill to General Eisenhower – 8th May 1944: “I am in this thing with you to the end, and if it fails we will go down together.” ...
Generalfeldmarschall Erwin Rommel 1891-1944
Rommel inspects the new beach defences
Allied HQ Southwick house, Portsomuth