You are free to choose the topic of the essay, but it should (1) relate to European integration, (2) relate to the period after 1919, and (3) be narrow enough to be able to say something meaningful. The essay should also include a brief introduction of 2-3 sentences and a brief conclusion of 1-2 sentences. Please use footnotes for the references. I placed two examples here, but feel free to ask me more questions if you need it.