_Infantry_.--Infantry constitutes, in active service, by far the most numerous portion of an army; in time of peace its duties are simple, and, in most countries, of little comparative importance; but in our country the continually recurring difficulties on the Indian frontiers, render this arm peculiarly necessary and important, even in time of general peace. From the nature of infantry service--no peculiar technical knowledge (we speak of the privates and officers of the lower grades) being so absolutely indispensable as in the other arms--the soldier may in a short time be trained and instructed in his duties. For this reason the ratio of infantry in a peace establishment is ordinarily much less than in active service, this arm being always capable of great expansion when occasion requires. [Footnote 31: In discussing our own organization, it may be well to compare it with the armies of some of the principal nations of Europe. Our limits will not allow us to go very much into details, nor to make a comparison with more than a single European power. We shall select France, inasmuch as her army organization has served as a model for the rest of Europe, and is still, in some respects, superior to most others.] In the early periods of society, and in countries where horses abounded, men have usually preferred fighting on horseback; but civilization and a more thorough acquaintance with war has always increased the importance of infantry. The Hebrews, and also the Egyptians, employed this arm almost exclusively. The Asiatics generally employed both infantry and cavalry, but with the Greeks the _infantry_ was the favorite arm. Even their kings and generals usually fought on foot. The Romans conquered the world mainly with their infantry. This arm was also considered of the greatest importance by the ancient Germans and Gauls; but the migration of the Huns and other Mongolic tribes mounted on small and fleet horses, and the acquaintance formed by the Franks of northern Spain with the Moors, who were mounted on beautiful horses from Arabia and the plateau of Asia, introduced a taste for cavalry in western Europe. This taste was still further cultivated under the feudal system, for the knights preferred fighting on horseback to serving on foot. During the crusades the infantry fell into disrepute. But the invention of gunpowder changed the whole system of warfare, and restored to infantry its former importance.