There is a temptation in writing History essays to want to show off as much knowledge as possible. Slotting in a particularly juicy piece of information at the right time will indeed be hugely useful. However, facts are not given their due weight if they are left unaided by any analysis. True, a large part of history consists in remembering a sufficiently large selection of facts which tell the story of a point in time. But these facts must also be bolstered by an argument which makes clear why precisely those facts are significant, what we should learn from them. In writing a History essay it's better to see yourself as someone who is taking an unfamiliar reader through historical territory they have not encountered before, describing but also explaining what happened. As many, if not more, marks are given for analysis than they are for factual content. Therefore, making sure your essay states a position at the beginning and supports that position with the aid of all those historical facts you know will raise your marks massively.