What is called a field company of Engineers is, roughly, of the same strength as an infantry company. It carries with it shovels for digging trenches, axes for cutting down trees, wire for making entanglements, sand-bags for protecting men firing from trenches, explosives, carpenters' and smiths' tools, water-supply stores, signalling apparatus, and the materials for making maps. All these things are carried in four-horsed carts and on the backs of pack animals. Six-horsed wagons are laden with the materials for building bridges, such as pontoons, trestles, planks, and so forth. An Engineer company can erect a bridge across a stream in a very short time, and take it down even more rapidly.
Engineers at work erecting a pontoon bridge over a river. Photo, Newspaper Illustrations, Ltd.
An army must be fed, or it cannot fight. This is what Napoleon meant when he said that an army marches on its stomach. The work of bringing food to an army or part of an army is entrusted to a very important branch of the service known as the Army Service Corps. Then there must be a Medical Corps, to look after the sick and wounded; a Flying Corps, for scouting purposes; and a Signalling Corps, to transmit messages from one part of the field to another. Signalling is done by "flag-wagging," by flashes of light sent from mirrors (heliographs[182]) or lamps, or by means of telegraphs, both wire and wireless, and by telephones. Our army is famous all over the world for its expertness in signalling. By means of relays of flag-waggers messages can be conveyed for fifty miles with great speed and certainty.
Signalling by means of two flags. Most signalling is now done by means of one flag.
On page [208] you will see a little picture which compares a man with an army. An army in the field is very like a man, as you will plainly see if you study the drawing.
First, let us look at the man's brain. By means of it he thinks, makes his plans, and orders all the movements of his body. What is called the staff of an army is the brain of the army. It plans how to outwit the enemy, thinks out ways and means, and controls the movements of all the troops.