History of military logistics
In 1915, as many as 25 per cent of the rounds in a batch might be defective. The shortage of ammunition created a political crisis in the UK, the Shell Crisis of 1915, which led to the formation of a new coalition government.
As munitions production increased, transport became the major bottleneck. Military logistical systems continued to rely on nineteenth-century technology. The British shipped 5,337,841 tonnes (5,253,538 long tons) of ammunition to France and 5,525,875 tonnes (5,438,602 long tons) of hay and oats to feed the animals. When the war began, the rail and horse-drawn supply were stretched to their limits. Where the stalemate of trench warfare took hold, narrow gauge trench railways were built to extend the rail network to the front lines. The great size of the German Army proved too much for its railways to support except while immobile. From the beginning of the Battle of the Somme on 24 June to 23 July 1916, 150,000 tonnes (148,000 long tons) of ammunition had been fired but only 103,404 tonnes (101,771 long tons) were landed, the difference being made up by depleting stockpiles. The capacity of the six channel ports that handled 96 per cent of the British Expeditionary Force’s requirements was increased and additional locomotives and rolling stock were imported. Between 1914 and 1918, the French laid between 5,000 and 6,000 kilometres of new track.

On the Western Front, supplies moved from the ports by rail or barge to regulating points where they were sorted before being forwarded. The supply system might be described as "semiautomatic". Certain supplies for which demand was invariant, such as fodder and rations, were sent daily without requisition in division-sized "packs" consisting of two wagons of bread, two of groceries, one of meat, four of hay, five of oats and one of petrol, a total of 15 wagons. Each pack was earmarked for a particular division and would be delivered to its own railhead. Supplies for which there was variable demand, such as reinforcements, remounts, ammunition and engineering stores, had to be indented, and were sent by the railway carload. A typical train would consist of forty wagons, two packs and ten other wagons. Each division drew its supplies from one railhead, although it might share it with other divisions.
The advent of motor vehicles powered by internal combustion engines offered an alternative to animal transport for moving supplies forward of the railhead. Though they generally require better roads and bridges, they were much faster and more efficient than animal transport. Compared with railways they had limited cargo capacity, and created logistical problems of their own with their need for fuel and spare parts. At one point the French used 11,200 trucks to move 100,000 men over 100 miles (160 km) at short notice. By 1918, the French had 90,000 motor vehicles, while the Germans had 40,000.
The movement of supplies posed greater problems on the Eastern Front, where the transportation system was less developed than in the west. The Russian economy was less developed and less efficient than that of Germany, and food and ammunition shortages developed in 1915. In turn, Russia was more developed industrially than Turkey, which nonetheless managed to last longer than Russia. This was partly because after the Gallipoli campaign the forces the British brought to bear in the Sinai and Palestine campaign and Mesopotamian campaign were in relatively remote areas of the Turkish Empire where the well-resourced  British forces had to overcome supply and transportation problems to bring their power to bear. The British were able to use motor vehicles in the invasion of Darfur but in sub-Saharan Africa they were heavily reliant on human porters.

The British blockade of Germany kept a stranglehold on raw materials, goods, and food needed to support the Germany war effort, and is considered one of the key elements in the eventual Allied victory in the war. This form of economic warfare also involved pressure on neutral countries not to export or re-export to Germany and a program of pre-emptive purchasing. The Germans attempted to exploit occupied countries like Romania and Ukraine for oil, grain and other resources. Although the Allies controlled most of the world's shipping, Germany's unrestricted submarine warfare showed the vulnerability of merchant shipping despite Allied naval superiority. The United Kingdom was particularly vulnerable to economic blockade, as it did not produce enough food to feed itself, importing nearly two-thirds of its food. Coal and food had to be rationed.
In 1912, the biochemist, Casimir Funk, theorised that beriberi, scurvy and rickets were all diseases caused by nutrient deficiencies, naming the missing nutrient chemicals "vitamines" and over the following decades, biochemists were able to isolate them. During the First World War, the troops in the Gallipoli campaign suffered from beriberi and scurvy because the British Army's ration was deficient in these vitamins. Unlike their counterparts on the Western Front, the troops were unable to supplement their diet with local produce. A type of scurvy in the form of septic sores known as "Barcoo rot" appeared among the Australian Light Horse in the Sinai campaign, for the same reason.

Second World War: The mechanisation of warfare that started in the First World War, added the maintenance needs of military aircraft, tanks and other combat vehicles to the burden on military logistics. Many nations, including Germany, continued to rely on horse-drawn transport. Trucks were expensive to produce and their production put additional strain on scarce resources such as rubber, steel and petroleum. Petroleum was a particular problem, as the world's major sources were under the control of the Netherlands, United Kingdom, United States and the Soviet Union. Efforts were made to step up the production of synthetic fuels and rubber, but the supply of these posed difficulties throughout the war, and they came under Allied air attack. Germany's motor vehicle industry was not well developed either. It therefore made sense to continue to rely on horse-drawn transport. In 1939 a German infantry division had 942 motor vehicles and 1,200 horse-drawn carts. Even this was hard to meet, and large numbers of civilian and captured British and French vehicles were employed. The multiplicity of types created problems with spare parts.

The forces of the United States and United Kingdom were fully mechanised, although the British and Americans used mules in North Africa, Italy and Burma. The British and Japanese also used elephants in Burma. In the South West Pacific, human porters were used. There was little civilian demand for four-wheel drive vehicles, which were more expensive than regular vehicles, so commercial firms saw little benefit in producing them. All armies entered the war with large numbers of two-wheel drive vehicles. The need for four-wheel drive soon became apparent, especially in the less developed parts of the world, and considerable manpower and materiel had to be devoted to road making and maintenance. Similarly, the American automotive industry had scant interest in heavy trucks for long-distance hauls; the US Interstate Highway System had not yet been built, and interstate commerce was the province of rail and water transport. The US Army gave a low priority to such vehicles until the need became acute.
The increased technological and administrative complexity was reflected in the proliferation of staff and paperwork. In the United States, the Army Service Forces inventoried 200,000 paper forms and eliminated 125,000 of them. Professional analysis and simplification of common procedures was undertaken using industrial engineering techniques developed by industry.
The German invasion of the Soviet Union in 1941 faced logistical failure when the Soviet Union did not collapse after the initial frontier battles. The summer invasion meant that fodder was available for the 625,000 horses amassed for the operation, but stocks of food were low, and their seizure alienated the local population. An invasion later in the year would have avoided this, but left less time for operations before the winter set in. The distances involved, the speed of the advance, and the poor road network all contributed to the logistical difficulties, and shortages of spare parts developed for motor vehicles, which were in short supply in the first place. The bridges over the Dnieper were demolished by the retreating Soviets, and use of the railway system was hampered by the different track gauge used in the Soviet Union. Transportation difficulties made it difficult to distribute stores like winter clothing. In 1942 the German forces in the Soviet Union began to integrate the materiel and manpower resources of the occupied regions into the German war effort.

Motor vehicles ran on tyres, but the supply of rubber to the Allies of World War II was curtailed when the Japanese overran the major sources of natural rubber. Imports to the United States dropped from 910,000 tonnes (900,000 long tons) in 1941 to 11,000 tonnes (11,000 long tons) in 1942. Fuel rationing and recycling measures were introduced to conserve tyres. The synthetic rubber industry in the United States grew from producing 8,400 tonnes (8,300 long tons) in 1939 to 810,000 tonnes (800,000 long tons) in 1944. Germany produced synthetic rubber and oil, much of it with slave labour at the IG Farben plant at Auschwitz .
The Japanese also captured the major sources of quinine. Malaria was a major medical and military problem in many theatres of war.