nsimms wrote:
IF breastworks, forest, towns, elevations, etc impact melee, then why wouldn't entrenchments? I'm going to be real disappointed if you tell me that they don't impact melee either but it would explain some of the 'bad' dice rolls that I've seen during melee.
Neither trenches nor hex terrain affect melee. IE forests and towns don't give a melee penalty to the attacker. Of terrain or entrenchments, only elevation, breastworks and hexside terrain (stone, fence, stream) penalize the melee attacker. And only if the terrain is given a non-zero combat modifier in the pdt file. For example, streams in Gettysburg do not affect melee or fire combat, whereas in Overland and Chickamauga they do. Hexside penalties can stack; some hexes have stream/fence hexsides, for example in Overland in the Wilderness.
Think of trenches as hex terrain and breastworks as hexside terrain.
Elevation affects combat by -20% (or whatever the pdt value is) per elevation change. Fire combat is only affected by up to a maximum of 2 elevation changes (ie only up to a maximum of -40%). Melee combat however has no upper limit on the amount of elevation changes. An elevation change of 5 gives a -100% malus to the attacker (ie the attacker can inflict no casualties on the defender unless they have some other additive bonuses to affect them). High ground is very good for melee defense and for defense in general since it works for both fire combat and melee combat.
In a melee with 1:1 odds, the attacker has only an 18.7% chance of succeeding. If the defender is one elevation higher than at least one attacker (all attacking units share the same bonuses and penalties in melee), the attacker has only a 10.6% chance of winning. For an elevation change of 2, the attacker has a 3.6% chance of winning. As of 3 or more elevation changes, the attacker has no chance of winning.
To return to the topic of fortifications, in a 1:1 melee across a breastwork, the attacker has only a 6.9% chance of winning in Gettysburg (-30% for breastworks) and a 1.1% chance in Overland (-50% for breastworks).