The battlefield was basically a narrow strip of land between the River Ouse and the cliffs of Hastings. The English held the western end of the hill, the right flank, with their longbowmen and infantry; the Normans had the eastern slope and the centre. The French knights were pushed into the centre by the Norman cavalry, and the tide of the tide was controlled by the river – the Normans could not cross it easily, so they kept the centre tight. In the final phases the English broke the Norman centre at the high point, and then the French left was left exposed. It’s a lesson in how a seemingly small geographic feature can dictate every manoeuvre; even the slightest hill or the curve of a river can decide a whole campaign. If you’re writing a chapter on it, keep a close eye on the exact distances and the angle of the hill, those are the numbers that make the story believable.