The fighting in the mountains of Afghanistan revealed some shortcomings in how the Army trains its infantry. This is nothing new. Five to ten years after the last war, training practices become more and more unrealistic. Next time there's a war, there is a sharp reality check. While the U.S. Special Forces and commandos "train as they fight," this is not the case with most other combat units. The 10th Mountain Division and 101st Airborne ran into a number of avoidable problems. One was the old problem of weight. The full load of an infantryman is some hundred pounds. Loaded down like that, moving through the mountainous terrain of Afghanistan was slow (about 2 kilometers an hour). Part of the problem was that the body armor was often not worn when training, although most troops recognize that the current armor is very effective even against rifle bullets and is essential. Peace time training also avoided things like digging a lot of fortifications (or even latrines), or learning how to ration water. The peacetime digging is avoided because you have to fill the trenches and foxholes back in, not a popular exercise. Water rationing is not popular with commanders because it risks dehydration problems, which can be dangerous to an officers career. Similar dangers (illnesses from bad water) from using water purification tablets is also avoided. But in Afghanistan, carrying less water and relying more on purifying local supplies would have made the troops more mobile. Dropping the rucksacks and traveling light would have made it easier to catch the enemy, and the lighter weight would have been a lot easier on the troops.
Another problem with peacetime training was the centralization of supply (makes it easier for the supply folks) and fire control (safety again.) In Afghanistan, it was obvious that the resupply should have been done at the company, not battalion, level. And platoon and squad leaders should have been trained to direct mortar fire. The fire control officers never seemed to be where you needed them most. And when they did get there, the enemy had often departed.
There were also problems with the air force, again, mainly because of a lack of realistic training in peacetime. The air force insisted on keeping their aircraft out of an area where the army was using mortars, even though the air force bombers were way above the reach of any army mortar shell. The air force also forgot that perpendicular attacks are much more likely to hit friendly troops. The al Qaeda also learned to spread their troops out, and keep moving, to reduce the effectiveness of smart bombs. This meant that the infantry had to chase after the small groups of enemy fighters. Mortars thus became much more important.
There were a lot of little mistakes that made things harder for the troops. Many units did not zero their weapons before going into action, thus making for less accurate shooting. Because of the high, dry and sunny climate, things like chapstick and sun block proved useful for the few soldiers that had these items. While kneepads have become more popular, and proved very useful in rocky Afghanistan, not all infantry sent into the mountains had this item. Despite all these failures, the U.S. troops defeated the enemy they encountered. But with more attention to these details, they would have done so more quickly and effectively.