<span>fight to defend the polis</span>
Try reading the first paragraph of this. It may help. https://books.google.com/books?id=IQwAAAAAMBAJ&pg=PA2&lpg=PA2&dq=How+does+columbus+and+smith+deploy+...
<span>The armies became immobile because of trench warfare. avoid the problem of fighting allied powers on two fronts. ... Economic hardships brought on by the war resulted in the downfall of the czar.</span>