3. Third line transport consists of "maintenance companies"— Royal Army Service Corps units equipped with heavy lorries. One company is provided for every division and cavalry division in the force, and for army corps troops, army troops and G.H.Q. troops in accordance with their requirements.
Working of the Supply and Transport System.—Supplies (and mechanical transport spare parts and stores) forwarded from the lines of communication are consigned by special trains to rail heads, i.e., the places where they leave the railway and are carried to their destinations by road. On reaching railheads they are taken over by the railhead supply officer, who issues them to the "main tenance companies" serving the divisions allotted to that railhead. The maintenance companies load in bulk for the brigades of their divisions, and their duty is to carry their loads as far as what are known as "refilling points," spots previously selected for the meeting of the "maintenance company" and the divisional train.
The latter takes over the supplies for issue in detail to units of the division, and its duty is to carry them from the "refilling point" to "delivery points," that is, to the first-line transport of the indi vidual unit. Variations may and normally are made in this system by the insertion of "rendezvous" between railhead and "refilling points," and of "meeting points" between refilling points and "delivery points"; and such insertions depend on the nature of the operations, requirements of concealment from air observation, state of congestion of the roads, or the tactical situation at the time. Thus there are normally two definite echelons of transport
between units and railhead which are available for the purposes of supply. This should permit troops to operate freely within oo m. of railhead.
The "mobile" supplies available are therefore as follows, assum ing the issue of rations to be from mid-day to mid-day as is normally the case : On the man, his iron ration and any uncon sumed portion of the previous day's issue. In the regimental first line transport, one day's supplies. With the divisional R.A.S.C., one day's supplies. The total therefore is from two to two-and-a half days, excluding the iron ration.
Turning to the question of ammunition, this is forwarded to ammunition railheads, located for various reasons quite apart from supply railheads. The maintenance company conveys both artillery and small arms ammunition, as in the case of supplies, to "refilling points." At these the divisional ammunition company, which forms part of the divisional R.A.S.C., takes over the am munition in their medium lorries. It normally carries the artillery ammunition to the batteries, but under certain circumstances it may be required to proceed to the divisional ammunition column— an artillery unit. The small arms ammunition is taken to the infantry or cavalry brigade reserve—this reserve being formed by a system of "pooling" a portion of the first-line transport of units.
These systems are specially designed to allow of elasticity. If distances are short, one echelon of transport may be dispensed with. If they are long, it may be necessary to interpolate an addi tional echelon—the necessary vehicles being found by the higher command from army corps or army resources.
As previously emphasized, the state of communications or the lack of them may demand the employment of pack carrier or even air transport for the whole or a portion of the "carry." But what ever the mode of conveyance, the principles remain the same. To sum up, they are : In the case of supplies, the maintenance within reach of the fighting troops of two days' complete rations and the "iron ration," and a daily delivery of one day's rations, petrol and forage to units. In the case of ammunition, the principle is to maintain, by a continuous replacement of expenditure, a definite establishment in rounds per gun, per automatic weapon, and per rifle throughout the echelons. The maintenance system, in its application to non-divisional units, is similar to that described above. Consequently, all types of fighting units are on the same basis as regards first-, second- and third-line transport.