starts at 0 ... atackers gains momentum gain points (1000/-1000) or vice versa.
when reaches 5000 win war ... if defenders reach -5000 they're able to defend.
to add complexity last 1000 points could be harder to get and easier for the opposing faction.
for example: 4000 (or any number here) to 5000 (and win) points gained could be like x0.75 and the oposing faction trying to re-gain momentum will have points x1.25. This was there could be some tactics involved ...