Pardon me while I ramble on a bit. This is primarily (or perhaps entirely) for my benefit. Consider it musing or work notes.
Geography dictates the battlespace. As a rule, soldiers aren’t herded together onto a broad, featureless plain, formed up into ranks and columns, and marched headlong at the opposing army doing precisely the same thing. Elevation, terrain flank anchors, concealment, lines of egress — these are considerations. This becomes obvious when one considers major battles, such as Bannockburn, Crecy, etc.