This technique is used to provide secrecy, deception, and dispersion in areas where enemy observation or attack is likely, but it requires more time, more detailed planning, and greater decentralization of control. Columns consist of units having the same rate of movement. Those having different rates of movement are assigned separate routes, or their movements are staggered along the same routes. When an unforeseen crossing of two columns occurs and no control personnel from a higher headquarters are present, the senior commander regulates the crossing, based on the situation and the missions of the two columns. The varying types of terrain over which troops must march present different problems for commanders, depending on the specific area of operations.
Weather conditions combined with terrain affect the mobility of marching troops.
Foot marching under adverse climatic conditions follows the same principles as under normal conditions. The differences depend on the physical limitations imposed by adverse conditions and the use of special equipment to overcome them. Restrictions imposed by weather extremes and terrain constitute the major change from operations in temperate areas. These restrictions can present major obstacles to the successful conduct of operations unless proper provisions are established. Movement in many areas of the world must be calculated in terms of time and distance.