The way military functions and the way on field battle occurs, have evolved because of the rapid change in the war zone due to technological advances. This is the reason why equipments related to military has evolved, developed and changed, becoming more productive and user friendly.
Military backpacks are the life saver of the soldiers on the ground and makes a lot of difference in their maneuverability, productivity and functionality. They should be made in such a way that it becomes easy for the soldiers to carry them while at the same time be very capable of fulfilling the large many functions military backpack is meant to achieve, which is a very tough thing to achieve simultaneously.
Military equipments including US military backpacks have undergone major change, for good, from the time when ALICE pack during Vietnam wars to now when highly upgraded MOLLE and ILBE which are amongst the few best military backpacks in the world, are used. The purpose of the best military backpack still remain the same, giving high mobility and easy functionality to the soldiers while being able to sufficiently carry all the tools, gadgets, equipments and accessories needed in the war zone to win against opponents and give an upper edge.
The MOLLE backpacks designed right after the ALICE load-carrying system had an up gradation also defined as inclusion of module system. It had pouches designed superiorly to make the soldiers more capable on site, where the equipments, ammo and personal weapons had its own space and was more easily reachable. It had a special system when the whole pack can be disconnected easily from the body on field whenever needed to ensure more productivity.
The newer and the latest version which was designed after the MOLLE system was the ILBE backpack system by the US Marines and it was far advanced than any of the other system introduced earlier. They are hard to find as they are the latest model, but the ALICE and MOLLE canvas military backpack are both easily available and used often by the campers, trekker and outdoor activities enthusiasts.
The ALICE military backpack system was the turning point in the world of backpacks and since the time they were used in the Vietnam war, the real use of backpacks started as it signified the importance and the use of it in the combat situations. However, they are outdated now and no more in service in the military, they are very popular among the civilians and used vastly by the people for mountaineering, camping, etc. CFP -90 was one of the US military backpacks which were used before the later two system were used after the ALICE load carrying system and is on record the first backpack system to use vest and pack advance system.
The military surplus backpack is those which are made available to the public for their personal use and this is the reason why the earlier back pack system are easy to find on net and shops. The newer backpack versions used currently by the military are not readily available to the public.