In any military operation, it is important first to know the lay of the land. When you know the distance to be traveled, then you can plan whether to proceed directly or by a circuitous route. When you know the difficulty or ease of travel, then you can determine the advantages of infantry or mounted troops. When you know the dimensions of the area, then you can assess how many troops you need, many or few. When you know the relative safety of the terrain, then you can discern whether to do battle or disperse.