Editing Total War: Warhammer/Tactics (section)

===Chokepoint Battle===

A variation of the above, and pretty much everything is the same, except there is a natural chokepoint between the two armies. Chokepoint battles are initiated when the attacker needs to cross an overworld terrain feature like a bridge or river-crossing. Generally, the defender gets to deploy over a wider area on their half of the field while the attacker's forces have a more narrow deployment zone, but this depends on where the armies are in relation to the obstruction. 

While "chokepoint" would make you think a single narrow pass like Thermopylae, most of the maps have 2 or 3 "chokes", so putting all your units to defend a single pass is an easy way to get yourself encircled.