with four cohorts in the first or front line, three in the second, and three in the third, as follows1:

29. Observe that the cohorts are arranged with intervals between them, that the cohorts in the second line are directly behind the intervals in the first, and that the cohorts in the third line are directly behind the intervals in the second. The cohorts are numbered from 1 to 10, according to the rank and military experience of the centurions and soldiers. A position in the front line is more honorable than in either of the others, while in either line a position on the right wing is more honorable than on the left. The first cohort, holding the post of honor, is on the

1 This order of battle is generally supposed to be the acies triplex, so often mentioned by Caesar, but General von Göler claims that the acies triplex refers, not to the three lines of cohorts, but to the three great divisions of an army, viz., the main body or the central division, and the two wings.

2 As the third line was held as a reserve, and was not often called into action, the exact position of the cohorts seems not to have been as definitely determined as in the other lines. The order here given has been adopted from Rüstow. Göler arranges the cohorts as follows:

3 Thus promotions both of centurions and of men were from the tenth cohort to the ninth, from the ninth to the eighth, from the eighth to the seventh, and so on through all the cohorts to the first.

extreme right of the front line, while the tenth, holding the lowest rank in the legion, is on the extreme left of the third line.

30. The interval between the cohorts in each line was 120 feet, the length of a cohort, but the interval between the lines was probably 240 or 250 feet. Thus the front or length of a legion in battle-array was 840 feet, while its depth from the front of the first line of cohorts to the rear of the third line was from 600 to 620 feet.1

31. When an army consisting of several legions was marshalled in order of battle, each legion was arranged in three lines, as already described, and the several legions were separated by intervals, probably varying in length with the nature of the ground, but seldom less than 120 feet, the length of a cohort. If we assume that this interval was 120 feet, we shall find that the front of Caesar's line of battle on the Axona, with six legions, was 5,640 2 feet and its depth, 600 feet. Thus the line of battle of an army of six legions, numbering in all about 25,000 men, was considerably more than a mile long and almost an eighth of a mile deep, and occupied upwards of 75 acres of ground.

OFFICERS IN A ROMAN ARMY.

32. In a Roman army engaged in an important work like the conquest of Gaul, the regular officers were the commander-in-chief, the lieutenant-generals, the quaestor, the military tribunes, the centurions, the praefects, and the decurions.

33. The commander-in-chief, called dux belli or imperator, had in his own province almost unlimited military power. He was clothed with the full measure of authority which belongs to a commander-in-chief in modern warfare.

34. The lieutenant-generals, legati, were the highest officers in the army under the commander-in-chief. They

=

1 The front, or length, of the legion was made up of the length of four cohorts and of three intervals, each 120 feet. It was therefore 7X120 840 feet. The depth was made up of the depth of the three lines of cohorts, each 40 feet, and two intervals, each 240 or 250 feet, i.e., it was 120+480 or 500 600 or 620 feet. 2 That is 6X840+5X120 5,040+600 5,640 feet.

were all of senatorial rank and received their appointment from the senate. In the absence of the commander-inchief, they assumed his duties. They were sometimes placed in command of important detachments detailed for special service. In the battle with Ariovistus, Caesar placed one of his legions under the command of his quaestor and each of the other five under the command of one of his lieutenants.

35. The quaestor had charge of the military chest, and was the quartermaster of the army. He had the rank of a lieutenant-general, legatus, and was sometimes entrusted with a command in battle.

36. The special officers of the separate legions were the military tribunes and the centurions.

37. Each legion had six military tribunes, tribuni militum, who formerly commanded in rotation, two at a time for a period of two months.1 In the army in Gaul, however, the tribunes were mostly young men of wealth and social position whom Caesar, from personal friendship or political considerations, had selected from the equestrian order and placed upon his staff. They had little military experience or knowledge, and were accordingly incompetent to take the general command of a legion in battle, though they were sometimes entrusted with the command of small detachments detailed for special service. In general, they administered the internal affairs of the legion. They served as staff-officers to the commander-in-chief and as adjutants to the lieutenant-generals and the quaestor.

38. Each legion had also 60 centurions. These officers were in general men of large military experience, who had been promoted from the ranks, as a reward of good service. They were the real commanders, not only of centuries, but also of maniples and cohorts, and, in a certain sense, under the legatus, of the legion as a whole. The two centurions in each maniple differed from each other in rank; the first,

1 The two tribunes commanded by turns, each for one day. See Marquardt, Römische Staatsverwaltung, Vol. II., p. 352; also Jähns, Geschichte des Kriegswesens, p. 225.

2 See Book I., 39.

3 According to Göler, there were 120 centurions in each legion, but he includes in this number the 60 assistant centurions, called optiones.