From the earliest recorded periods of the world, men have gone forth to war, for the purpose of destroying or overcoming their enemies, and with the chance of being themselves destroyed or overthrown. Public authorities have generally taken account of the number of their own men who have been wounded and killed in battle, and of the casualties in the opposing armies. Gunpowder and steel, and the manifold weapons, instruments, and means of destruction in the hands of the enemy are commonly considered as the principal, if not the only sources of danger to the soldier, and ground of anxiety to his friends; and the nation reckons its losses in war by the number of those who were wounded and killed in battle. But the suffering and waste of life, apart from the combat, the sickness, the depreciation of vital force, the withering of constitutional energy, and the mortality in camp and fortress, in barrack, tent, and hospital, have not usually been the subjects of such careful observation, nor the grounds of fear to the soldier and of anxiety to those who are interested in his safety. Consequently, until within the present century, comparatively little attention has been given to the dangers that hang over the army out of the battle-field, and but little provision has been made, by the combatants or their rulers, to obviate or relieve them. No Government in former times, and few in later years, have taken and published complete accounts of the diseases of their armies, and of the deaths that followed in consequence. Some such records have been made and printed, but these are mostly fragmentary and partial, and on the authority of individuals, officers, surgeons, scholars, and philanthropists. It must not be forgotten that the army is originally composed of picked men, while the general community includes not only the imperfect, diseased, and weak that belong to itself, but also those who are rejected from the army. If, then, the conditions, circumstances, and habits of both were equally favorable, there would be less sickness and a lower rate of mortality among the soldiers than among men of the same ages at home. But if in the army there should be found more sickness and death than in the community at home, or even an equal amount, it is manifestly chargeable to the presence of more deteriorating and destructive influences in the military than in civil life. SICKNESS AND MORTALITY IN CIVIL LIFE. The amount of sickness among the people at home is not generally recognized, still less is it carefully measured and recorded. But the experience and calculations of the Friendly Societies of Great Britain, and of other associations for Health-Assurance there and elsewhere, afford sufficient data for determining the proportion of time lost in sickness by men of various ages. These Friendly Societies are composed mainly of men of the working-classes, from which most of the soldiers of the British army are drawn.