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 role (duty
or job) of the infantry, whether offensive or defensive, is the role 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.