When do rebellions turn into a battle for the capital?

Oddly enough, this is not entirely obvious and can be apparently paradoxical:

... ‘multipolar’ civil wars are fought nearest to the capital, while ‘bipolar’ conflicts are fought substantially further away and ‘unipolar’ conflicts are fought largely in the periphery. Multipolar wars exist where the government and two or more rebel groups are evenly matched (Afghanistan in the early 1990s is an example). Bipolar wars exist where the government and one rebel group are evenly matched (such as in Rwanda in 1994) and unipolar wars exist where the government is much stronger than the rebels (such as the numerous ethnic insurgencies in Myanmar). The study also showed that internally divided rebel groups are more likely to fight in capital cities.

The paper: ‘Capital punishment’: Bargaining and the geography of civil war

Quote taken from: Why Was There No “Battle for Baghdad”? 

found at excellent: Political Violence @ a Glance