Historical fact is being diluted by Hollywood fiction, with some young people believing that Gandalf the wizard masterminded the defeat of the Spanish Armada.
Almost half of 16- to 34-year-olds questioned in a BBC poll did not know that Francis Drake led the English fleet against Spain. One in five 16 to 24-year-olds thought it was Columbus, while one in 20 said it was Gandalf, the wizard from Tolkien's The Lord of the Rings.
The figures, which were released to mark the start of Battlefield Britain, a new BBC series fronted by the veteran election presenter Peter Snow and his son Dan, were declared "really surprising" by history specialists. Campaigners for a return to a more traditional syllabus branded the results a "disgrace" for the state education system.
Showing the impact of Hollywood on history, 15 per cent of 16- to 24-year-olds thought that when Orangemen march in Northern Ireland on 12 July, they were celebrating victory at Helmsdeep, a battle at the end of The Two Towers, the second novel in Tolkien's trilogy.
Of the 1,006 adults over the age of 16 who took part in the survey, only half of all age groups knew that the marches mark the Battle of the Boyne, in which the Protestant William of Orange defeated the troops of King James II in 1690.
Despite the blanket coverage in the media of the recent 60th anniversary of D-Day, a third of those polled and half of 16- to 34-year-olds did not know that the Battle of Britain took place during the Second World War. More than one in 10 among 16- to 24-year-olds thought it was part of the Hundred Years War against France 600 years earlier.
The Roman occupation of Britain proved equally unmemorable, with one in five unaware that they had been here at all. One in 10 of 16- to 24-year-olds thought that the Germans had conquered Britain.
But revealing that it is not just the young who display historical ignorance, 22 per cent of over-65s did not remember that the Romans had conquered Britain, with one in 20 saying that it was the Germans.
"Some of the results are really surprising," said Peter Furtado, the editor of History Today magazine. "Since the collapse of the grand Whig narrative that Churchill was talking about in A History of the English-Speaking Peoples and which went out of favour with the rise of multi-cultural Britain, it's been very difficult for anybody to construct a large story of Britain. It seemed that Simon Schama did it ver y well in A History of Britain, but clearly someone needs to have another try," Mr Furtado said.
Nick Seaton, the chairman of the Campaign for Real Education, said: "It's an absolute disgrace to the state education system that young people are coming out with such a lack of historical knowledge."
The education watchdog, Ofsted warned last month that secondary schools spend "insufficient time" teaching pupils about the British empire. Peter Snow commented: "It's at once a shock and a challenge that so many people can be so wrong about some of the key moments in Britain's past."Reuse content