People's lack of basic knowledge (historical or otherwise) can sometimes astound me.
For example, I was in a pub in Horsham and heard a young woman bemoaning to her male companion that people had laughed at her at work earlier that day. Someone had asked her if she knew France, to which she'd replied "Yes. I know that there's a place called Dover-Calais because I've seen ferries to it advertised on the sides of buses". So, despite living less than 100 miles from Dover, she was unaware that it's a British port and thought that she 'knew' France because she's heard of a (non-existent) town there!
However I have to admit that my knowledge of history isn't that great. I certainly couldn't place all English monarchs in order and I've no real idea (or inclination to find out) which were Tudors, Plantagenets or whatever.
Trafalgar? Isn't that where King Henry the Fifth offered his kingdom for a horse in a battle against Napoleon (who'd crossed the Alps with elephants), while wearing a balaclava and a cardigan, before getting an arrow in his eye?