Should be done as a report.
Should also think about the following:
Militarism, Alliances, Nationalism, Imperialism, Assassination.
Should have introduction, body paragraphs, and conclusion (which of the above in M.A.N.I.A or combination of above caused the war) 
Use PEEL:
P= Point

E = Evidence/Example

E = Explain

L = Link

Make sure to have an thesis statement in introduction.