Everything you need to know ahead of the 75th anniversary of the Normandy landings.
Royal Marines land at Normandy in June 1944 (Picture: PA).
1. D-Day was supposed to happen a day earlier
The original date for D-Day was set to be 5 June 1944.
The landings had been planned with very specific weather and tides conditions in mind, but as the day approached, the weather got worse and unpredictable. High winds and torrential rain meant the operation had to be delayed.
3. Normandy was seen as an unlikely point for an attack
An attack from the sea was not foreseen by the Germans.
In order to succeed in a military invasion of Normandy, the attacking forces needed to not only make it successfully onto the beaches with their military equipment, but they would need to either carry their military and food supplies with them or have them shipped over.
This is why Calais was the location Germans believed an attack could take place: the distance from England was shorter than that between the UK and Normandy, and there was a large, active port.
A game of deception code-named 'Bodyguard' was put into action by the Allies.
Operation Fortitude built up to the 1944 Normandy landings. Divided into the North and South sub-plans of deception, it aimed at misleading the German high commands as to where an invasion would take place.
Phantom field armies, made up of inflatable vehicles and submarines, were placed in strategic locations to simulate threats on Norway (Fortitude North) and Pas de Calais (Fortitude South).
Thanks to Operation Fortitude, German reinforcements were delayed to reach Normandy when the attack finally took place.
5. D-Day was the largest single-day amphibious invasion in history
Planning for Operation Neptunetook months and it began in 1943.
It involved 6,939 vessels and 4,126 landing crafts which assembled on 5 June 1944 off the Isle of Wight.
The landings on the shores of Normandy were preceded by an airborne assault to the German troops stationed in France and naval bombardments.
The 80 km stretch of coast was divided into five sectors: Utah, Omaha, Gold, Juno, and Sword.
6. Spies helped with the success of D-Day operations
Despite the German occupation of France, resistance groups were still active and spies and saboteurs of the Nazi regime kept close contacts with the Allies.
The Special Operations Executive was set up in 1940 to help resistance movements in Germany-occupied territories thrive despite the occupation.
Informants in France provided the Allies with intelligence on German defences and carried out acts of sabotage to disrupt the German war effort.
Many of the resistance activities revolved around the rail network in France ahead of D-Day. Saboteurs took care of deliberately damaging railways around Normandy and slowing down transport services as well as industrial military factory production.
7. Brits could not travel to Ireland in the lead up to D-Day
All travel to Ireland was barred from 12 March 1944. Ireland was one of the neutral countries during the Second World War.
Even though Ireland never blocked Allied forces aircraft from using the Donegal Corridor, and even though Irish and Allied intelligence tacitly cooperated during the war, it was decided to stop all travel to Ireland ahead of D-Day.
This decision was taken to prevent information concerning the date of D-Day to be leaked.
8. The Luftwaffe was greatly outnumbered
The German Air Force, known as the Luftwaffe, was outnumbered 30:1 on D-Day.
Because of the highly strategic nature of the D-Day operations, the German Navy and the German Air Force had little means to resist the invasion.
The Luftwaffe had withdrawn nearly all its fighters to counter American daylight bombing operations over Germany so there were very few aircraft left in France.