The
Latin word
castra,
[1] with its singular
castrum, was used by the ancient Romans to mean buildings or plots of land reserved to or constructed for use as a military defensive position. As the word appears in both
Oscan and
Umbrian (dialects of
Italic) as well as in
Latin,
[2] it probably descended from
Indo-European to
Italic. The diminutive form
castellum was also used for the smaller forts, and the generic term
praesidium ("garrison post") was also used. The terms
stratopedon ("army camp") and
phrourion ("fort") were used by
Greek language authors. In English, the terms
Roman Camp and
Roman Fort are commonly used for the
castra.
The best known type of castra is the camp, a military town designed to house and protect the soldiers and their equipment and supplies when they were not fighting or marching. Regulations required a major unit in the field to retire to a properly constructed camp every day. "...as soon as they have marched into an enemy's land, they do not begin to fight till they have walled their camp about; nor is the fence they raise rashly made, or uneven; nor do they all abide ill it, nor do those that are in it take their places at random; but if it happens that the ground is uneven, it is first leveled their camp is also four-square by measure, and carpenters are ready, in great numbers, with their tools, to erect their buildings for them." [3] To this end a marching column ported the equipment needed to build and stock the camp in a baggage train of wagons and on the backs of the soldiers.
Camps were the responsibility of engineering units to which specialists of many types belonged, officered by architecti, "chief engineers", who requisitioned manual labor from the soldiers at large as required. They could throw up a camp under enemy attack in as little as a few hours. Judging from the names, they probably used a repertory of camp plans, selecting the one appropriate to the length of time a legion would spend in it tertia castra, quarta castra, etc., "a camp of three days", "four days", etc.[4]
More permanent camps were castra stativa, "standing camps". The least permanent of these were castra aestiva or aestivalia, "summer camps", in which the soldiers were housed sub pellibus or sub tentoriis, "under tents". Summer was the campaign season. For the winter the soldiers retired to castra hiberna containing barracks of more solid materials, public buildings and stone walls.
