It is probably worth mentioning - especially in an open-ended subject like philosophy - that the reason your teacher is being so vague is that he really doesn't care about the actual answer, but rather the aim of the exercise is to see if you are capable of forming an opinion about a subject, and then supporting that opinion via a well-written, well-researched essay.
If so, then your focus should be on forming that opinion (whatever it may be) doing the research to pull up supporting facts, and then crafting it all together into a single, cohesive, and compelling whole.
The thing to remember is that an essay is a very specific type of document. It is an argument, in which you are trying to sway someone to your point of view without being physically present. Unlike debate or discussion, there is no back-and-forth in an essay; it (and its argument) must stand on its own merits.
There is a formal structure to an essay: topic sentence and introduction, supporting arguments, each with a cited fact or example (usually best grouped in threes) and a summary and conclusion.That structure is important - it is the bones upon which you flesh out your argument. If you haven't been taught this already, do some reading on the hows and wherefores of essay writing.
The meat of your essay is the supporting arguments and the cited facts that support them in turn. This is where you can get a lot of help here, as you can get leads on potential facts from lots of regular forum members (as you are doing now)
But the start point is to come up with your topic sentence; the point you intend to prove. One might be "While the demands of the battlefield require a more authoritarian approach than is typically found in civiallian life, soldiers are not mindless drones following orders, but rather have considerable leeway to decide their own fate". Another might be "While soldiers are required to surrender certain aspects of their free will during the conduct of their duties, the end result of that surrender, when tied to responsible and moral political leadership, is a net positive for the community as a whole".
Etc.
Good luck!
DG