Operation Overlord

Normandy was chosen over the shorter crossing to the Pas-de-Calais because it was less heavily defended, lay within fighter range of southern England, and offered beaches sheltered from the prevailing westerlies by the Cotentin peninsula. The assault frontage ran fifty miles from the Vire estuary in the west to the mouth of the Orne in the east.

Two features shaped everything that followed. Caen sat at the eastern hinge, on open ground suited to armour and covering the direct road to Paris. The German command concentrated its panzer divisions there for that reason, and the city took thirty-three days to fall. Behind the American beaches lay the bocage: centuries-old earth banks topped with hedge, dividing the country into thousands of small fields, each one a prepared defensive position invisible from the air. It cancelled the Allied advantage in tanks and aircraft, and cost more casualties than the landings did.

Overlord was run by a coalition command with no precedent: an American supreme commander with British deputies at sea, in the air and on the ground, directing forces from a dozen nations under one operational plan. It held together because Eisenhower spent more effort on holding it together than on operations, and the arguments over Caen are still being had eighty years later.

The German command in the West was divided in a way that proved fatal on the day. Armoured reserves were split three ways between Rommel's Army Group B, Rundstedt's OB West, and an OKW reserve only Hitler could release. Hitler was asleep. Rommel wanted the tanks on the coast, Rundstedt wanted them massed inland, and the compromise left neither with what he needed.

Overlord was planned around one assumption: that no major port would be captured intact and in working order. Everything below follows from it. Landing craft had to beach and retract on open sand; two artificial harbours had to be built from concrete towed across the Channel; fuel had to come through a pipeline on the seabed.

The second theme is quality against quantity. German armour was individually superior and never available in numbers that mattered; Allied armour was outclassed in a straight exchange and arrived in quantities the defence could not absorb. In the bocage the advantage went to the defender; in open country under clear skies it went to the Sherman and the rocket-firing Typhoon.

The foundation record is Gordon A. Harrison's Cross-Channel Attack, the US Army's official history, written with access to captured German records and to participants still living. Against it sit the operational papers at the National Archives, the naval action reports held by the Naval History and Heritage Command, and the photographic collections of the Imperial War Museums, NARA, the Bundesarchiv and The D-Day Story.

Accounts conflict on several points: casualty figures at Omaha, the number of men who escaped the Falaise pocket, whether Montgomery's Caen strategy was designed or improvised. Where they do, this record says so rather than choosing a side. Front lines and force areas drawn on the map are approximate, generalised from the daily situation maps, and show shape and movement rather than survey positions.