Military logistics
Etymology and definition: The word "logistics" is derived from the Greek adjective logistikos meaning "skilled in calculating", and its corresponding Latin word logisticus. In turn this comes from the Greek logos, which refers to the principles of thought and action.  Another Latin root, log-, gave rise around 1380 to logio, meaning to lodge or dwell, and became the French verb loger, meaning "to lodge". Around 1670, the French King Louis XIV  created the position of Maréchal des logis, an officer responsible for planning marches, establishing camp sites, and regulating transport and supply. The term logistique soon came to refer to his duties. It was in this sense that Antoine-Henri Jomini referred to the term in his Summary of the Art of War (1838). In the English translation, the word became "logistics". 

In 1888, Charles C. Rogers created a course on naval logistics at the Naval War College. In Farrow's Military Encyclopedia (1895), Edward S. Farrow, and instructor in tactics at West Point provided this definition:Bardin considers the application of this word by some writers as more ambitious than accurate. It is derived from Latin logista, the administrator or intendant of the Roman armies. It is properly that branch of the military art embracing all the details for moving and supplying armies. It includes the operations of the ordnance, quartermaster's, subsistence, medical, and pay departments. It also embraces the preparation and regulation of magazines, for opening a campaign, and all orders of march and other orders from the general-in-chief relative to moving and supplying armies. 
The term became popularised during the Second World War. In Logistics in World War II: Final Report of the Army Service Forces, Lieutenant General LeRoy Lutes, the commanding general of the Army Service Forces, gave the term a more expansive definition: The word "logistics" has been given many different shades of meaning. A common definition is: "That branch of military art which embraces the details of the transport, quartering, and supply of troops in military operations." As the word is used in the following pages, its meaning is even broader. It embraces all military activities not included in the terms "strategy" and "tactics." In this sense, logistics includes procurement, storage, and distribution of equipment and supplies; transport of troops and cargo by land, sea, and air; construction and maintenance of facilities; communication by wire, radio, and the mails; care of the sick and wounded; and the induction, classification, assignment, welfare and separation of personnel. 
NATO uses a more restrictive definition:The science of planning and carrying out the movement and maintenance of forces. In its most comprehensive sense, the aspects of military operations which deal with: 
In the 1960s, the term "logistics" began to be used in the business world, where it means physical distribution and supply chain management. This is more restricted than the military definition.
Logistics is an enabler of military operations, not an end in itself. Poor logistics can result in defeat, but even the best logistics cannot guarantee victory. Conversely, the best possible logistics is not always required: fit for purpose can suffice.

Principles: Historian James A. Huston proposed sixteen principles of military logistics:

Equivalence: Strategy, tactics and logistics are inseparable and interdependent facets of military art and science.
Material precedence: Mobilisation of materiel should precede that of personnel, and the provision of logistical units that of combat units.
Forward impetus: The impetus of supply should be from the rear, and combat unit commanders should be spared having to deal with logistical details while still being in control of their logistics.
Mobility: Logistics should facilitate the rapid movement of both combat and logistical units in support of operations.
Dispersion: Multiple sources of supply and lines of communications reduce the enemy interference and congestion of transportation infrastructure.
Economy: Logistical resources are limited, so they must be deployed so as to make the best use of them.
Feasibility: Logistical capabilities are subject to external constraints.
Flexibility: Strategic and operational plans and priorities change and logistical support must change with them.
Relativity: Logistics is relative to time and space.
Continuity: Fundamental changes should not be required to meet an emergency.
Timeliness Logistical tasks must be accomplished so as to take full advantage of opportunities.
Responsibility: Someone must be responsible for logistical performance and outcomes.
Unity of command: Logistics is a function of command and a single authority should be responsible for logistics.
Information: Accurate and timely information is required for effective logistical planning and support.
Quality: Logistics is facilitated by strict quality standards.
Simplicity: Simple solutions are more effective and manageable.
The United States Joint Chiefs of Staff reduced the number of principles to just seven:

Responsiveness: Providing the required support when and where it is needed.
Simplicity: fosters unity and efficiency in planning and execution, and reduces the fog of war and the "friction" caused by combat.
Flexibility: the ability to improvise and adapt to changing situations and requirements.
Economy: using the minimum amount of resources required to bring about an objective.
Attainability: the point at which sufficient supplies, support and distribution capabilities exist to initiate operations at an acceptable level of risk.
Sustainability: the ability to maintain the necessary level and duration of logistics support to achieve objectives.
Survivability: the capacity to prevail in spite of adverse impacts.

Supply options: There are three basic options for the supply of an army in the field, which can be employed individually or in combination.

Obtain supplies in the field: The most basic requirements of an army were food and water. Foraging involved gathering food and fodder for animals in the field. The availability of these tends to be seasonal, with greater abundance around harvest time in agricultural regions. There is also a dependence on geography, for in desert campaigns there may not be food, water or fodder available locally.
Looting was a means of obtaining supplies in the field. It is possible to capture supplies from the enemy or enemy population. An alternative is purchasing, whereby an army takes cash and buys its supplies in the field. Cash can also be obtained in the field through local taxation, backed by the threat of violence. The major drawback of using local sources of supply is that they can be exhausted if an army remains in one place for too long, so a force dependent on local supply needs to keep moving.
The widespread use of resources in the field gives rise to counter-logistics, whereby they are denied to the enemy through devastation of the land and removal or destruction of resources. Pre-emptive purchasing can be used as a form of economic warfare. A besieging force can attempt to starve out a garrison or tempt it to sally through devastation of the surrounding area rather than undertake the more costly operation of assaulting and destroying it, but if it is dependent on local supply then the besieger who might be starved out through their exhaustion.

Carry supplies with the army: A second method is to bring along what is needed, whether by ships, pack animals, wagons or carried on the backs of the soldiers themselves. Since ancient times, troops had carried rations and personal equipment such as weapons, armour, cooking gear and bedrolls. Animals could be driven to accompany the army and consumed for meat. Roads facilitate the movement of wheeled vehicles, and travel by river or sea permits the carriage of large volumes of supplies. This allowed the army some measure of self-sufficiency, and until the development of faster firing weapons in the 19th century most of the ammunition a soldier needed for an entire campaign could be carried on their person or in wagons accompanying the troops. However, this method led to an extensive baggage train which could slow the army's advance.

Ship supplies from the rear: Obtaining supplies in the field and carrying supplies with the army remained the primary means of supply until the 19th century, but even in the 17th century the much larger armies of the period were highly dependent on food supplies being gathered in magazines and shipped to the front. Starting with the Industrial Revolution, new technological, technical and administrative advances permitted supplies to be transported at speeds and over distances never before possible.
At the same time, increased demands for ammunition, and the heavier weight of shells and bombs made it more difficult for armies to carry their requirements, and they soon became dependent on regular replenishment of ammunition from depots. At the same time, mechanisation, with motor vehicles replacing animals, created a demand for fuel and spare parts, neither of which could be obtained locally. This led to a "logistical revolution" which began in the 20th century and drastically improved the capabilities of modern armies while making them highly dependent on this method.

History: The history of military logistics goes back to Neolithic times. The most basic requirements of an army were food and water. Early armies were equipped with weapons used for hunting like spears, knives, axes and bows and arrows, and rarely exceeded 20,000 men due to the practical difficulty of supplying a large number of soldiers. Large armies began to appear in the Iron Age. Animals such as horses, oxen, camels and elephants were used as beasts of burden to carry supplies.
Food, water and fodder for the animals could usually be found or purchased in the field.
The Roman Empire and Maurya Empire in India built networks of roads, but it was far less expensive to transport a ton of grain from Egypt to Rome by sea than 80 kilometres (50 mi) by road.