How did Belgium, a neutral country, become a “flashpoint” in the war?

no every country is held to the same degree as others just some member countries such as the usa and germany are more economically sound so the need to show there support to all others  

polisit can also mean a body of citizens. in modern historiography, polis is normally used to indicate the ancient greek city-states, like classical athens and its contemporaries, and thus is often translated as "city-state". the body of citizens came to be the most important meaning of the term polis in ancient greece.