The Great Amphibious Invasion: D-Day, 6 June 1944

Jozef Straczek

One of the clearest demonstrations of sea power occurred on 6 June 1944, when the Allies landed in German-occupied Normandy in the greatest sea-borne invasion in history. Operation OVERLORD was the culmination of four years of maritime operations against the Axis forces in the European theatre. In the space of a day the Allied forces gained a foothold in occupied Western Europe that could not be dislodged, and which formed a bridgehead for subsequent operations that would drive German forces progressively back toward their ultimate defeat in 1945.

Following the Allied defeat in France in 1940, Adolf Hitler prepared his forces for Operation SEA LION, the planned amphibious assault on Great Britain. German control of both the air and sea were imperative for the conduct and sustainability of such an operation. Due to the success of the Royal Air Force in the Battle of Britain and ongoing Royal Navy (RN) operations, Germany never gained sufficient command of the sea or air to hazard such a risky venture. The operation was cancelled on 12 October 1940 when Hitler's priority shifted to Operation BARBAROSSA and the invasion of the Soviet Union. As well as contributing to the defence of Great Britain from invasion the RN was responsible for ensuring the safe passage of convoys carrying vital supplies, men and equipment to the United Kingdom from America and the British Empire that allowed the war to continue against the Axis.

After Pearl Harbor and Hitler's declaration of war on America the armed forces and, perhaps more significantly, the industrial might of the United States joined the war in Europe. Shipyards in America were crucial to the war effort, as not only were they building and repairing warships of all types, but also constructing merchant ships and a variety of specialised amphibious craft. These amphibious craft would form the backbone of the future D-Day invasion force.

Planning for an Allied return to the continent had commenced in 1941, with Stalin pushing for a Second Front in Europe from 1942. The Casablanca Conference in January 1943 set 1944 as the year for the invasion of France. At the Tehran Conference in November 1943, Roosevelt and Stalin forced Churchill to commit to a firm invasion date of May 1944. General Eisenhower was appointed the Supreme Allied Commander for Operation OVERLORD. Once the invasion decision had been made planning commenced in earnest. The date subsequently changed to June 1944 after two invasion beaches were added to the plan, necessitating a month delay to obtain additional landing craft and transport aircraft.

Admiral Sir Bertram Ramsay, RN was appointed the Naval Commander and given responsibility for organising Operation NEPTUNE, the naval element of Operation OVERLORD. This was no simple task, as sufficient forces had to be built up, equipped, sustained, and transported across the Channel to France. The movement of thousands of ships of various sizes had to be carefully choreographed to ensure that they arrived at the right time in the right place to perform their allotted tasks. Prior to the assault, minefields and other obstacles had to be cleared and channels marked for the landing craft. During the assault phase other warships were to bombard enemy forces ashore, and to protect the transports and support ships from enemy submarines, surface craft and aircraft. Still more warships were required to maintain a blocking force in the North Sea to prevent German surface units in the Baltic impeding the invasion, while other escorts would continue to protect convoys to and from the United States and Russia, and support operations in the Mediterranean and the Pacific.

After the initial landings the assault and follow-on forces required stores, ammunition, fuel, reinforcements, and casualty evacuation. Because most of Europe was still under Axis control, all logistic support to the invasion and follow-on forces had to be provided across the Channel from England. While very limited support could be, and was, provided to advanced land forces by parachute drop or glider, the massive size of the invasion force required the bulk of support to be provided from the sea.

Initial planning for the operation quickly identified problems with the obvious landing area of the Pas de Calais. Not only were the German defences much stronger, the landing beaches were too narrow and would only allow a force of two divisions in the first wave, increasing the vulnerability of the landing force. Following extensive analysis of possible landing sites the beaches of Normandy were chosen. These beaches allowed for the initial landing of five infantry divisions supported by three Airborne divisions[1] on a 50-mile front in an area where, though geography favoured the defenders, the German defences were not very strong.

The amassing of the necessary ships, support craft and aircraft to move this force took time, as the Allied war effort was spread between Europe and the Pacific. Compromises on equipment allocation between theatres were necessary despite the 'Germany First' policy. The date of the assault was initially set for 5 June, to meet the requirements of a half tide at dawn, to allow landing craft to cross the German beach obstacles, following a night with a full moon, to allow for the pre-landing parachute drops of the Airborne divisions. The invasion was subsequently delayed for 24 hours to 6 June to take advantage of a gap in a storm front passing over the English Channel.

Once the executive order was given an armada of nearly 7000 ships and small craft began to move, crewed by over 195,000 naval personnel. The force consisted of: 1212 naval combatants, ranging from battleships to motor torpedo boats; 4126 landing ships and assault craft; 736 ancillary ships and support craft; and 864 merchant ships. On the night of 5 June, 97 minesweepers commenced clearing channels for the invasion force. This hazardous task was made more difficult by the poor weather conditions. The assault forces passed down the swept channels and took up their allotted positions. At 02:00 troops began to embark in the assault craft. The landings commenced at 06:30 and achieved complete tactical surprise. German maritime and air operations against the invasion force were uncoordinated and ineffective, particularly in the face of overwhelming Allied air superiority and sea control.

During the assault phase 6 battleships, 2 monitors, 23 cruisers, 101 destroyers, 17 frigates, 21 corvettes, 6 sloops, 30 trawlers, 17 patrol craft, 228 specialised gun and rocket armed landing craft, and a host of coastal craft provided bombardment support to the soldiers ashore and protected the transports and support ships from enemy submarines, surface craft and aircraft. While over 12,000 Allied combat aircraft, including fighters, ground attack, tactical bombers, and heavy bombers, supported the landings, both before and during 6 June, naval fire support was crucial to overcoming the enemy defences, particularly the coastal guns. Eisenhower noted in his post battle report that "no instances were found of damage done by bombs perforating the covering shields. Such of the guns as were silenced had been so reduced by shellfire through the ports". [2] The shore bombardments at Gold, Utah, Juno and Sword beaches were particularly effective, silencing the German counter battery fire and disrupting beach defences and troop movements behind the beaches. By the end of the day the German beach defences had been neutralised, around 133,000 troops had landed across the beaches, another 23,400 troops had landed from the air, and the greatest concern of the Allied command was the weather.

Allied naval and air units also strove successfully to neutralise German naval attempts to disrupt the landings and the resupply effort. In the days following the invasion eleven U-boats, two destroyers, fifteen E-boats, two torpedo boats and forty smaller craft were destroyed, and five U-boats and a destroyer badly damaged. Allied losses in return comprised a destroyer, two frigates, three landing ships, three cargo ships and nine smaller vessels sunk.

Following the successful lodgement on the Normandy beaches the land forces had to be sustained and reinforced. During the period 7 to 30 June, 570 Liberty ships, 788 coasters, 905 Tank Landing Ships, 1442 Tank Landing Craft, 180 troop ships, and 372 Large Infantry Landing Craft arrived off France. By the end of June ships had transported 861,838 personnel, 157,633 vehicles and 501,834 tons of supplies to France. Coupled to this effort were the continuation of the Atlantic supply line from the east coast of North America to the United Kingdom and the convoys from the United Kingdom to Russia.

British X-Craft on the surface
British X-Craft on the surface.

More than 2500 Australians took part in the D-Day operation, in the air, on land, or at sea. Although no Royal Australian Navy (RAN) ships were present, Australian naval personnel, mainly members of the RAN Volunteer Reserve (RANVR), did serve in or command landing craft, coastal craft and warships of the naval force. One notable individual was Lieutenant Ken Hudspeth, RANVR, who commanded the X-Craft (midget submarine) X20. Prior to the planned departure of the invasion force X20 crossed the Channel to take up a submerged position off Juno Beach. On the night of 4 June X20 surfaced to pick up a BBC broadcast, which contained a coded message that the invasion was postponed. This meant another 18 hours in the cramped, smelly, humid submersible.

On the night of 5 June the coded message indicated the invasion was to proceed. Hudspeth and his crew mounted and checked their equipment. As the pre-invasion bombardment commenced they turned on their radar beacon and shone a light to seaward to allow the assault craft to navigate to the correct beaches. For his part in the invasion Lieutenant Hudspeth was awarded a third Distinguished Service Cross. He had received the first award for his part in the attack on the Tirpitz in 1943 and the second in January 1944 for beach reconnaissance operations in preparation for the D-Day landings.

Meanwhile, half a world away, Australian forces in the South West Pacific were an integral part of amphibious operations in General Douglas MacArthur's drive toward the Philippines. These operations were complicated by being launched and sustained from farther away than simply 100km across the English Channel, as there was no significant industrial or logistic support closer than Australia. Harbours and repair facilities had to be created, logistics stockpiles, troops and naval units amassed in forward areas, and forward airfields captured or constructed.


  1. 1st US Infantry Division (including elements of the 29th US Infantry Division), 4th US Infantry Division, 3rd British Infantry Division, 50th (Northumbrian) Infantry Division, 3rd Canadian Infantry Division, 82nd US Airborne Division, 101st US Airborne Division, 6th British Airborne Division.
  2. Report by The Supreme Commander To The Combined Chiefs of Staff On the Operations in Europe of the Allied Expeditionary Force 6 June 1944 to 8 May 1945, p 21.