Despite radical changes in the technology of war on weapons effectiveness, the effects of the terrain remain relatively the same. A hill is still a hill and still provides observation of an resistance to movement. It is still easier to move on smooth ground which tends to use the corridors, valleys and ridges created by water erosion.
The changes in lethality in the land battles of the 20th Century brought to full effect the technologies of the last half of the 19th Century. While massed fires of massed troops were used against massed targets of infantry and cavalry of the Napoleonic era continued through the US Civil War until the net effects of barbed wire, machinegun fire, and the artillery shell forced troops formerly in the open to move out, spread out, dig in and/or hide. The trench and the tank afforded protection of fighting forces.
Artillery using shells detonating on impact in large numbers from breach loading howitzers spread shell fragments laterally across the impacted battle area in effect creating grazing fires while air bursts created plunging fires from shell fragments making areas distant from forces on the front lines as lethal as those in front. This caused dispersion of forces well away from the front lines.
By comparison, warfare prior to WW 1 preferred relatively level terrain in order to keep the closed ranks necessary for massed fires in order and not broken by the folds of the ground that now offers cover and concealment for dismounted infantry.
In conducting terrain analysis for units on the forward edge of the battlefield (that which is in direct eyeball and ear shot), the attractiveness (or lack thereof) of terrain is subject to the same effects throughout time. An avid student of self survival in combat can learn valuable lessons from the battlefields of over two thousand years.
Fighter pilots use their hands to depict air to air combat. I suggest the use of hands in a similar fashion showing the relations of terrain features, movement and fires.