S.L.A. Marshall explains modern supply chains (in The Soldier’s Load and the Mobilty of a Nation) in 1950:
The greater becomes the mobility and carrying capacity of an army’s transport system, the stronger becomes the necessity for keeping the supply system fluid, for reducing surpluses all along the line from the factory to the front, and for G-4′s learning to sleep without dreaming of disaster because he has no strategic reserve.
In industry or in military organization, what is the final justification for putting more money into an improved transportation system? Simply that it is the best way to forestall the waste that comes of warehousing, stockpiling and deterioration of goods. To develop yet greater road speed and dependability in military transport serves a valid strategic purpose only in the measure that it enables us to reduce the supply burden. It simply defeats its own ends if it finally builds up supply volume until it chokes movement and drains the fighting line of needed manpower. Tactical strength depends on fighting power based on freedom to supply the combat troops. But oversupply will as surely stifle that freedom as overproduction will impair the prosperity of a civilian economy.
Only the matériel moved and used contributes to success in war. That which remains stored is a gift to the enemy.
He then veers into what’s coming militarily:
Highly mobile advanced bases, field bases that scarcely need to resort to dumping, ports that measure their capacity in the speed of the tum-around of the carriers in both directions, maintenance crews as adept with a Tommy gun as with a grease gun-these things mean the kind of strategic mobility the future requires.
It is said that we are entering an era of area warfare, and that at last the old alignments are gone forever. Fronts may be anywhere; guerrilla warfare will be the normal order. Any link in the communications zone will be in danger of being overrun.
[…]
The more fluid the form of war, the more necessary it is for flexibility to be the main characteristic both of the machinery and the lrainiPg doctrine. That is the logical counter to the increased range and killing power of today’s decisive weapons. As the threat rises against all rear installations, wholly new requirements will be imposed on military organization. And chief among them that all soldiers be trained for fighting — that the rear be supplied with mobile counteroffensive power — and that the structure of the rear avoid massiveness, and acquire a new mobility.
Ah, the birth of the “just in time” supply system. As brittle as it is awful. Especially in war, where the enemy always has a say, and considers supplies to be juicy targets.
People are terrible at forecasting actual requirements, much less fulfilling those of others. Never mind the incredible stockpiles of munitions, fuel, food, water, spare parts, and replacements required to sustain a real offensive.
Huge supply depots are efficient. They are also incredibly vulnerable targets, whose loss can be crippling. A plethora of small depots are inefficient, and each is vulnerable to a modest attack. But an attacker is unlikely to destroy them all, and the loss of a few is relatively insignificant.