On June 6, 1944, D-Day marked the start of the Allied invasion of Normandy, the greatest amphibious operation in history.
Codenamed Overlord, this vast cross-Channel attack enabled the UK, the USA and their allies to land substantial forces on mainland Europe during World War Two.
Allied leaders agreed that establishing a second front in north west Europe and relieving the pressure on the Russians on the Eastern Front was essential in order to defeat Nazi Germany.
They chose Normandy as the location for the D-Day landings, despite the Calais area offering a much shorter Channel crossing. Normandy had excellent landing beaches, was less fortified than Calais and was still within fighter aircraft range.
Extensive training took place in the UK in the months leading up to D-Day, ranging from divisional exercises to individual training to prepare soldiers for the assault. At the same time, a huge build-up of materiel took place, with the south of England beginning to resemble a huge military camp packed with vehicles, tanks, supplies and soldiers from many nations.
Thousands of air reconnaissance photographs of the German defences were taken. Special forces teams landed on the coast to gather information. Others worked with the French resistance to gather intelligence on German troop dispositions and carry out acts of sabotage against transport and communication networks.
A fleet of ships and landing craft crossed the channel. Heavy bombing, along with a massive naval bombardment, destroyed many of the German defences. Assault troops then landed on five beaches.
Airborne forces were dropped behind the beaches and on their flanks to slow down German counter-attacks.
Bridges, road crossings and coastal batteries were seized to help the amphibious forces advance inland.
To keep the invasion secret the beaches were given codenames: Utah, Omaha, Gold, Juno and Sword.
The US Army was the western invasion force, landing on Utah and Omaha beaches. Omaha was the most heavily defended of all five beaches and the Americans suffered high casualties there during the invasion.
The eastern invasion force was made up of British troops, landing at Gold and Sword beaches, and the Canadians, landing at Juno. These beaches were closer to Caen, which the Allies were planning to liberate.
The British met with relatively weak defences and succeeded in meeting up with the paratroopers dropped earlier.
This was not the case for the Canadians at Juno. The heavily fortified defences and rough seas meant that they too suffered many losses.
But the Allies’ deception plans had worked brilliantly. The destination of the landings remained a secret and the Germans were convinced that a second, larger attack would take place elsewhere. Much-needed German troops were held back in other regions awaiting an invasion that never took place.
The initial German response was slow and poorly co-ordinated. The generals couldn’t move their armoured reserves without Hitler’s approval.
The Allies suffered at least 10,000 casualties on June 6, 1944, ten times the number of German losses.
And many of the immediate strategic objectives of the landings were not achieved, including the failure to capture any of the key towns.
But D-Day was still a huge success. More than 150,000 Allied troops had crossed the Channel and established a foothold in France.
Their task now was to drive the Germans into retreat...
On August 25, 1944, Paris was liberated. With the Germans in full retreat, the Allies now advanced rapidly on a broad front through north-east France and Belgium towards the borders of the Third Reich.
D-Day and the Battle for Normandy are often seen as the beginning of the end for Hitler. But Germany’s defeat would probably have occurred even without Operation Overlord, given the huge casualties sustained fighting the Soviets on the Eastern Front.
However, the landings certainly hastened the end of the war in Europe, drawing in forces that might otherwise have slowed the Soviet advance to Berlin.
D-Day also ensured that the Western Allies were firmly established on the Continent at the war’s end, thus providing a counter to Soviet-backed communism at the start of the Cold War.