This chapter discusses the land battle of the 1990s: constant and changing factors in conventional warfare on the modern battlefield as seen from the perspective of the front-line ground forces commander. Battlefield mobility suffers, because the technology for overcoming the obstacles and facilitating continued maneuver is lagging. Mobility and transferability are mitigated by natural and man-made obstacles. These tend to centralize movement, channeling ground forces into inferior and vulnerable venues, limiting flexibility, and delaying progress. Most of the battlefield area is outside the commander's line of sight. Technology is beginning to change this, as 'look down' observation technologies "which used to be very rare and completely dependent on air power are accessible by other means and might be indigenous and available to the ground force." Warfare was fundamentally an engagement between the forward edges of two formations whose depths were hidden and inaccessible to one another.