Royal Marines Commandos land on a Normandy beach on 6 June 1944 (Picture: PA).
A new study has revealed more than half of the British public do not know exactly what D-Day is.
A poll by the Royal United Services Institute (RUSI) and YouGov found only 49% of people questioned could select the correct term used to describe D-Day.
Those taking part in the study were given five terms which could describe D-Day, with 3% selecting 'the day the UK declared war on Nazi Germany' description as the correct answer.
Meanwhile, 15% choose 'the day when Nazi Germany surrendered to Allied Forces' option and 13% said 'the UK evacuation of France'.
A total of 16% said they did not know or that none of the options were correct.
Also when asked 'Who were the Allied Forces fighting on D-Day?', only 57% of people correctly chose Germany from a list of suggested enemies.
Lord Peter Ricketts, from RUSI and the Normandy Memorial Trust, said:
"Over the decades, memories of the courage and sacrifice of those who took part in the biggest amphibious landings in history begin to fade.
"That is why it is so important to re-tell the story of what happened on the shores of Normandy in 1944 and why the lessons of that time are still relevant today."
Nearly 1,800 adults from the British public were questioned in the survey.
Defence analyst Christopher Lee said many are more familiar with "famous battles":
"We have in this country a glitter view of warfare, so we know famous battles like Trafalgar and Waterloo, but when it gets to 1805, they wouldn't know."
The results come as the nation prepares to mark 75 years since the Normandy Landings with commemorations in both the UK and northern France.
Further findings from the study showed 83% of people believed military actions in the Second World War were justified.
However, as the years have gone on, the popularity of military actions in war has generally decreased, according to the survey.
60% of people felt military actions were justified in the Falklands War, 32% in the Kosovo War, 25% in the 2001 Afghanistan invasion and 23% in the 2003 Iraq invasion.