The Wealth of Nations by Part 5 Chapter 1 Page 9

husbandmen, therefore, goes to war, the whole people cannot take the field together. The old men, the women and children, at least, must remain at home to take care of the habitation. All the men of the military age, however, may take the field, and, in small nations of this kind, have frequently done so. In every nation the men of the military age are supposed to amount to about a fourth or a fifth part of the whole body of the people. If the campaign, should begin after seed-time, and end before harvest, both the husbandman and his principal labourers can be spared from the farm without much loss.

He trusts that the work which must be done in the meantime can be well enough executed by the old men, the women, and the children. He is not unwilling, therefore, to serve without pay during a short campaign, and it