Every efficient officer must realize the possibilities and limitations of his own arm of the service as well as the possibilities and limitations of the other arms. Each arm of the service is necessary and important. A proper understanding of the use of the combined arms is as essential to success in battle as coöperation between the different members of a football team is to its success. Don't "knock" any arm but the one you are in, and don't knock that unless you are willing to admit you are not man enough to improve it.
INFANTRY
"The infantry is the principal and most important arm, which is charged with the main work on the field of battle and it usually decides the final issue of the combat." (Field Service Regulations.) The rôle (duty or job) of the infantry, whether offensive or defensive, is the rôle of the entire force. If it fails, all fail. When properly supported by artillery, trained infantrymen armed with rifles, bayonets, and the will to put the enemy out of action, will settle all issues.
ARTILLERY
The chief duty of the artillery is to support the infantry. It does this in three ways: 1st, By firing at the hostile infantry. 2d, By putting out of action the hostile artillery so that it cannot fire at the infantry. 3d, By demolishing the obstacles in front of the enemy's works. It smothers the enemy with a curtain of fire, so that the infantry can move forward without ruinous losses. Coöperation with the infantry is essential. If the infantry is defeated the artillery covers its withdrawal; if the infantry is successful the artillery moves forward and assists in reaping the full reward of victory by firing on the fleeing enemy. The present European War has greatly increased the prestige and importance of this arm of the service. The amount of artillery on the Western front and the amount of ammunition consumed daily is appalling.
CAVALRY
This very important arm is the eye with which the general sees for many miles to the front and flank. In an advance it pushes ahead, combs the country for the enemy, disperses his cavalry, and thus protects the infantry in the rear. It locates the enemy, and occupies his attention until the infantry comes up. It protects the flanks and rear of the infantry and artillery during the fight. If needed, it joins in the fight. If the infantry is defeated it covers the withdrawal, and if the infantry wins it pursues and pounces upon the enemy.
MACHINE GUNS
Before the present European War, machine guns were classified as emergency weapons. It was not believed that they could remain long in action, because they would soon be silenced by hostile fire (artillery and infantry). It was recommended, therefore, that a favorable opportunity be awaited before opening fire which was to be delivered with their utmost effectiveness. They were believed to possess very limited possibilities in an attacking line, hut as being most valuable in defensive works where protection and concealment could be found.
During this war they have lost, as a defensive weapon, no prestige. They have also proved of great value to the attacking side. They are being made light and portable to accompany the firing line in an attack. The supply of ammunition alone limits the number that can be used.