In a more advanced state of society, two different causes contribute to render it altogether impossible that they who take the field should maintain themselves at their own expense. Those two causes are, the progress of manufactures, and the improvement in the art of war.
Though a husbandman should be employed in an expedition, provided it begins after seedtime, and ends before harvest, the interruption of his business will not always occasion any considerable diminution of his revenue. Without the intervention of his labour, Nature does herself the greater part of the work which remains to be done. But the moment that an artificer, a smith, a carpenter, or a weaver, for example, quits his workhouse, the sole source of his revenue is completely dried up. Nature does nothing for him; he does all for himself. When he takes the field, therefore, in defence of the public, as he has no revenue to maintain himself, he must necessarily be maintained by the public. But in a country, of which a great part of the inhabitants are artificers and manufacturers, a great part of the people who go to war must be drawn from those classes, and must, therefore, be maintained by the public as long as they are employed in its service,
When the art of war, too, has gradually grown up to be a very intricate and complicated science; when the event of war ceases to be determined, as in the first ages of society, by a single irregular skirmish or battle; but when the contest is generally spun out through several different campaigns, each of which lasts during the greater part of the year; it becomes universally necessary that the public should maintain those who serve the public in war, at least while they are employed in that service. Whatever, in time of peace, might be the ordinary occupation of those who go to war, so very tedious and expensive a service would otherwise be by far too heavy a burden upon them. After the second Persian war, accordingly, the armies of Athens seem to have been generally composed of mercenary troops, consisting, indeed, partly of citizens, but partly, too, of foreigners; and all of them equally hired and paid at the expense of the state. From the time of the siege of Veii, the armies of Rome received pay for their service during the time which they remained in the field. Under the feudal governments, the military service, both of the great lords, and of their immediate dependents, was, after a certain period, universally exchanged for a payment in money, which was employed to maintain those who served in their stead.
The number of those who can go to war, in proportion to the whole number of the people, is necessarily much smaller in a civilized than in a rude state of society. In a civilized society, as the soldiers are maintained altogether by the labour of those who are not soldiers, the number of the former can never exceed what the latter can maintain, over and above maintaining, in a manner suitable to their respective stations, both themselves and the other officers of government and law, whom they are obliged to maintain. In the little agrarian states of ancient Greece, a fourth or a fifth part of the whole body of the people considered the themselves as soldiers, and would sometimes, it is said, take the field. Among the civilized nations of modern Europe, it is commonly computed, that not more than the one hundredth part of the inhabitants of any country can be employed as soldiers, without ruin to the country which pays the expense of their service.
The expense of preparing the army for the field seems not to have become considerable in any nation, till long after that of maintaining it in the field had devolved entirely upon the sovereign or commonwealth. In all the different republics of ancient Greece, to learn his military exercises, was a necessary part of education imposed by the state upon every free citizen. In every city there seems to have been a public field, in which, under the protection of the public magistrate, the young people were taught their different exercises by different masters. In this very simple institution consisted the whole expense which any Grecian state seems ever to have been at, in preparing its citizens for war. In ancient Rome, the exercises of the Campus Martius answered the same purpose with those of the Gymnasium in ancient Greece. Under the feudal governments, the many public ordinances, that the citizens of every district should practise archery, as well as several other military exercises, were intended for promoting the same purpose, but do not seem to have promoted it so well. Either from want of interest in the officers entrusted with the execution of those ordinances, or from some other cause, they appear to have been universally neglected; and in the progress of all those governments, military exercises seem to have gone gradually into disuse among the great body of the people.
In the republics of ancient Greece and Rome, during the whole period of their existence, and under the feudal governments, for a considerable time after their first establishment, the trade of a soldier was not a separate, distinct trade, which constituted the sole or principal occupation of a particular class of citizens; every subject of the state, whatever might be the ordinary trade or occupation by which he gained his livelihood, considered himself, upon all ordinary occasions, as fit likewise to exercise the trade of a soldier, and, upon many extraordinary occasions, as bound to exercise it.
The art of war, however, as it is certainly the noblest of all arts, so, in the progress of improvement, it necessarily becomes one of the most complicated among them. The state of the mechanical, as well as some other arts, with which it is necessarily connected, determines the degree of perfection to which it is capable of being carried at any particular time. But in order to carry it to this degree of perfection, it is necessary that it should become the sole or principal occupation of a particular class of citizens; and the division of labour is as necessary for the improvement of this, as of every other art. Into other arts, the division of labour is naturally introduced by the prudence of individuals, who find that they promote their private interest better by confining themselves to a particular trade, than by exercising a great number. But it is the wisdom of the state only, which can render the trade of a soldier a particular trade, separate and distinct from all others. A private citizen, who, in time of profound peace, and without any particular encouragement from the public, should spend the greater part of his time in military exercises, might, no doubt, both improve himself very much in them, and amuse himself very well; but he certainly would not promote his own interest. It is the wisdom of the state only, which can render it for his interest to give up the greater part of his time to this peculiar occupation; and states have not always had this wisdom, even when their circumstances had become such, that the preservation of their existence required that they should have it.
A shepherd has a great deal of leisure; a husbandman, in the rude state of husbandry, has some; an artificer or manufacturer has none at all. The first may, without any loss, employ a great deal of his time in martial exercises; the second may employ some part of it; but the last cannot employ a single hour in them without some loss, and his attention to his own interest naturally leads him to neglect them altogether. Those improvements in husbandry, too, which the progress of arts and manufactures necessarily introduces, leave the husbandman as little leisure as the artificer. Military exercises come to be as much neglected by the inhabitants of the country as by those of the town, and the great body of the people becomes altogether unwarlike. That wealth, at the same time, which always follows the improvements of agriculture and manufactures, and which, in reality, is no more than the accumulated produce of those improvements, provokes the invasion of all their neighbours. An industrious, and, upon that account, a wealthy nation, is of all nations the most likely to be attacked; and unless the state takes some new measure for the public defence, the natural habits of the people render them altogether incapable of defending themselves.
In these circumstances, there seem to be but two methods by which the state can make any tolerable provision for the public defence.
It may either, first, by means of a very rigorous police, and in spite of the whole bent of the interest, genius, and inclinations of the people, enforce the practice of military exercises, and oblige either all the citizens of the military age, or a certain number of them, to join in some measure the trade of a soldier to whatever other trade or profession they may happen to carry on.