Conclusions should be a round-up of your overall argument without majorly repeating the points in your essays! You want to start them with your final statement e.g 'the economy was the biggest factor in the fall of Weimar Germany.' and then continue by discrediting the other points in your essay and concisely explaining why they aren't as strong as your judgement factor.
Conclusions should be only slightly shorter than your original paragraphs but should be engaging, easy to understand and non-repetitive with your essay content, ending with a very clear and convincing judgement..