His ascension to the throne of England marked the end of the Wars of the Roses (read about them HERE and HERE). He's the man who finally managed to unify the houses of Lancaster and York.
But let's take it from the top.
Henry Tudor was born in 1457 to Edmund Tudor, Earl of Richmond, and Margaret Beaufort, who descended from the House of Lancaster. His mother was 13 years old when she gave birth to him and 12 years old when she... ahem... conceived him. Now, by comparison, the sex scenes in the Knock Knock film don't seem that creepy anymore, do they?