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Bill Thayer

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This webpage reproduces an article in
The Classical Journal
Vol. 36, No. 6 (Mar. 1941), 337‑345.

The text is in the public domain.

This page has been carefully proofread
and I believe it to be free of errors.
If you find a mistake though,
please let me know!

 p337  Caesar's Camp on the Aisne

Caesar's camp on the Aisne (B. G. II.8.3‑5) has usually been identified with excavations made by Col. Stoffel for Napoleon III near Mauchamp, northeast of Berry-au‑Bac.​1 To this Holmes reluctantly assents, stoutly maintaining that the excavations do not agree with Caesar's text, and leaves the way open to reconsideration should future excavations at Chaudardes prove more satisfactory.

The text is as follows:

Ubi nostros non esse inferiores intellexit, loco pro castris ad aciem instruendam natura opportuno atque idoneo, quod is collis ubi castra posita erant paululum ex planitie editus tantum adversus in latitudinem patebat quantum loci acies instructa occupare poterat, atque ex utraque parte lateris deiectus habebat et in fronte leniter fastigatus paulatim ad planitiem redibat, ab utroque latere eius collis transversam fossam obduxit circiter passuum CCCC et ad extremas fossas castella constituit ibique tormenta conlocavit, ne, cum aciem instruxisset, hostes, quod tantum multitudine poterant, ab lateribus pugnantes suos circumvenire possent. Hoc facto duabus legionibus quas proxime conscripserat in castris relictis ut, si quo opus esset, subsidio duci possent, reliquas VI legiones pro castris in acie constituit.


I present herewith a plan of the excavations:

[image ALT: A map of a small area showing the confluence of the Aisne River in NE France and the Miette its tributary, some hills between them with a Roman army on them, and an army of the Belgae on the opposite, north, bank of the Miette. The map is commented in detail in the text of this webpage.]

Holmes' objections are 1) that the line is not drawn up pro castris, 2) that the slopes of the hill are not in accord with the text, 3) that the six legions cover only part of the hill, 4) that the trenches protect only the right flank. Rutherford's effort​2 to reconcile these  p339 difficulties, at first defended by Holmes, was later rejected as being biased by prejudgment of the correctness of Napoleon's plan.

I believe that a re-examination of the text and the consideration of certain factors which Holmes ignores will show that Rutherford is essentially correct, and that the hill of Mauchamp agrees more nearly with Caesar's text than Holmes admits.

1) According to Holmes the acies is not pro castris. Rutherford explains that pro castris "proves that Caesar was looking westward towards the Aisne along the axis of the hill." Holmes humorously sees in this only disproof, for "the front of the camp . . . was that side of it which faced the enemy; and the side of this particular camp which faced the enemy was confessedly the north." This error, he continues, forced Rutherford also to mistranslate in fronte as "that end of the hill's ridge furthest removed from the camp." He further argues that since Caesar says ex utraque parte [collis] lateris deiectus habebat, and that the hill was just wide enough to receive the acies, Rutherford must be wrong in defending a map which places the acies alongside of the camp. Holmes's criticism appears at first sound. It is clear, however, that he has misrepresented Rutherford. He nowhere takes cognizance of the fact that at the base of Rutherford's view lies the supposition that Caesar thought of the west side of the camp as the front. Holmes has attacked only the superstructure of Rutherford's theory, and has unfairly ridiculed it without ever meeting the main problem. He has clearly assumed that the question of "front" is a simple topographical problem which can be negatively answered by a glance at the map. This is not so. Holmes has not considered that what he calls the front (north) may not be what Caesar would have called front. Rutherford did, for he saw that Caesar's description fits just as well with the west side of the camp as the front. This is what he meant by assuming that Caesar was looking along the axis of the hill. Rutherford, however, goes too far to the west as Holmes did to the north, for the map shows that the hill really runs northeast and southwest.​3 Actually, that which "faces the  p340 enemy" is no side of the camp at all, but the west corner. From this point a person facing the enemy would be looking diagonally along part of the hill, and then across the marsh, and consequently as truly along the axis of the hill (Rutherford) as across it (Holmes). Pro castris may therefore be either northwest or southwest, depending on the position taken by the individual. But to one truly facing the enemy, it would be more the latter than the former, for it was on the southwest that the open hilltop lay. This means that pro has been rather loosely used where the lay of the land did not conform to the book rules into which Holmes tries to force the excavations.​4 Clearly Caesar's description has lost a little of its clarity because local conditions forced the camp, but not the acies, to be at an angle of forty-five degrees to the enemy.

Further evidence that the southwest was the logical front is the fact that there were two gates on that side. Though clearly marked on Napoleon's plan, Holmes mentions this double gate only in another connection.​5 Moreover, the west side is that from which troops would issue to form the battle line, and I cannot see why, under these circumstances, the side employed in forming against the enemy should not strategically and logically be called the "front," regardless of the interior arrangements of the camp, or of Napoleon's naming of gates. This is infinitely more important than petty arguments concerning compass directions; it shows again that the west may well have been the front in the mind of Caesar.

2) In fronte — where the hill descends gradually to the plain — Holmes takes as the north, where the slope, however, is not very  p341 gradual. Rutherford's view of in fronte as the west agrees with the text, for Holmes admits that the western slope is so extremely gentle that it could not be described by lateris deiectus. In accord with our revised directions it is now the north and south, not the east and west, which have lateris deiectus. Furthermore, the marsh, which Caesar does not mention until after the text cited above, is merely described as inter nostrum et hostium exercitum. This descriptive detail, being in no way connected with the description of the hill, fit both the site and Napoleon's plan. Thus we are again enabled to interpret either the north or west as lateris deiectus, for the marsh curves around from north to west.

Holmes states that the hill descended gradually in front, that there was a marsh in front, and that Caesar drew up six legions in front. Therefore if a battle was intended, it must have been in the marsh. The refusal of either party to cross and the Belgians' subsequent flank attack confirm this. Why, then, did not Caesar write in fronte . . . fastigatus paulatim ad paludem redibat, instead of ad planitiem?​a Perhaps it is because in fronte may refer as much to the west (where there is less marsh) and northwest, i.e., where the planities was, as to the north (Holmes' fronte), which was all marsh. This does not, of course, mean that Caesar intended to attack down the narrow west end, but it does mean that as one looked from the front of the camp toward the enemy, one saw not only part of the marsh to front right, but also the planities along the axis of the hill.

3) If the hill is the true site, no appreciable variation from the arrangement of the legions as given by Napoleon is possible. But Holmes maintains that the legions are not drawn up pro castris and that the position of the Napoleonic camp proves the hill to be longer than a space adequate for only six legions, which Caesar distinctly says was the limit of the hill. I have shown above that the legions may definitely be considered as having been drawn up pro castris, but does Caesar's measurement of the hill invalidate the choice? Holmes is unwarranted in assuming throughout that the acies instructa was the six legions which Caesar subsequently used. Caesar had eight legions when he first looked at the hill. He used  p342 only six in the acies, it is true, and he wrote after the event. But is this any proof that when he mentally measured the hill before pitching camp he measured with only six legions in mind? If he measured with eight in mind, the hill fits; if he measured with six in mind, it may be that he measured with the camp space also in mind, knowing at the time that his arrangements would be as they were. He has merely omitted to tell us that he was leaving camp space outside of the calculations.​6 The fact that Caesar wrote with full knowledge of the number of legions he used does not favor Holmes' argument, for he also wrote with full knowledge that the camp space took space from the line. The truth is that from the text we cannot tell whether the hill was six or eight legions long.7

Furthermore, what evidence is there that when the acies was finally drawn up all six legions were on the hill? Whether or not the west slope was ad planitiem, it is gentle enough to permit fighting, or at least serve as a starting point. Therefore no absolute limit can be placed on the extent of the left wing. It may have stood on appreciably lower ground than the right and center. Here again, a fair consideration of the evidence leaves the way open of that identification without controverting Caesar's text.

4) Doubt cast on the Caesarean origin of the redoubts does not apply to the trenches as a whole, or in any way compromise the camp site. If the trenches are Caesar's, they support the theory that the north is the side and the west the front. The declivities according to Caesar were ex utraque parte, i.e., not in fronte, which was fastigatus paulatim. Therefore the trenches were at right angles to the deiectus, i.e., to the sides. On this hill the trenches run at right  p343 angles to the north and south edges; therefore the north and south are the sides. Conversely the north is not the front, and again Rutherford's view is shown to suit the text.8

The main difficulty is that the trenches appear to protect only the Roman right, whereas Caesar said ab lateribus pugnantes suos circumvenire.​9 This is an incontrovertible contradiction only so long as one assumes, as all have assumed, that a flank movement must come from the flank which is about to be attacked. Whether or not one agrees with Rutherford that the acies should be shifted slightly counter-clockwise so that the left rests on the Aisne, the fact remains that the Roman left was adequately protected from a flank attack by the Aisne and Miette. But, if one realizes that Caesar, too, knew his left was thus protected from a flank attack, and if one remembers that he used the word circumvenire, and may have wished to prevent a rear attack on the left flank, i.e., from the east, around the camp and along the north bank of the Aisne, then the south trench was exactly the proper defense to prevent it. In this way the north trench becomes the protection for the right flank, and the south trench for the left.

The sole valid objection​10 to the site is the gentleness of the west  p344 slope (according to Holmes' interpretation) or the only less gentle north slope (according to Rutherford's). Whichever slope is taken as having deiectum should be steeper. But, provided only the "sides" be steeper than the "front," we may not be so seriously disturbed by differences in degree. It is difficult, even with Gudeman's aid,​11 to pronounce how steep a deiectus must be. It may be doubted that Caesar was so strictly accurate as to invalidate a choice otherwise so suitable. We have already shown that the hill, though by no means the neat rectangular protuberance which Holmes' ideal translation would have, does not conflict with the topographical requirements of the Latin. Other sites, even better attested, show similar debatable points,​12 and the hill of Chaudardes  p345 affords different, but greater difficulties. There is no other choice, and in the face of evident military works consisting of a camp and two trenches, dating back before any records of modern warfare on a hill which fulfills all external requirements — that is, it is on the Aisne, next to another hill, with marsh between, near a ford, near the road leading northwest from Durocortorum — it would be past the bounds of coincidence to doubt the identification.

May we not, then, revise Holmes' final words: "The topography of Mauchamp, with the very important exception of deiectus, conforms somewhat more closely than Chaudardes to Caesar's description; but the results of Stoffel's excavations cannot be reconciled with Caesar's text except by Rutherford's forced interpretation," to read, "The topography of Mauchamp, with the minor exception of deiectus, conforms very closely to Caesar's description, and the results of Stoffel's excavations are easily correlated with the text of Caesar"?

The Author's Notes:

1 Napoleon III, Histoire de Jules César: Paris (1865‑66), Planche 8. The map is most easily available in T. Rice Holmes, Caesar's Conquest of Gaul2: Oxford (1911), facing p71. For Holmes' discussion cf. pp660‑668.

Thayer's Note: See this commentary by Holmes on the de Bello Gallico — not identical, but essentially similar to the work by him cited in the above note; in somewhat dishevelled Web formatting.

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2 W. G. Rutherford, Caesar, Bks. II‑III: New York, Holt (1880), 55 f. Cf. Holmes, op. cit.,1, 646‑651, where he at first defended Rutherford's view.

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3 Holmes omitted directions in his map, probably because north was to the top of the page.

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4 A somewhat similar loose use of prepositions occurs in 9, where the Belgae forded the Aisne quod esse post nostra castra demonstratum est. The Aisne is post castra only if post is the opposite of pro and if pro is understood as the north side of the hill; but that part of the river which the Belgae forded is not post under any circumstances, being west and south of the camp. The exact spot is, of course, conjectural even in Napoleon's plan, but that it was not directly behind the Roman camp is proved by the Belgians' plan to cross the river before attacking the bridgehead and, even should the attack fail, to continue into the fields of the Remi. Post, therefore, is understandable only as being loosely applied to the river in general, part of which, though not the part under discussion, was behind the camp.

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5 Cf. von Göler, Caesars Gallischer Krieg: Freiburg (1880), II, 251; III, 38; and Taf. XVII, fig. 5a. Von Göler adopts the view that the north(west) side is the front, for the gate on that side is marked porta praetoria.

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6 The hill is not wide enough for the camp to be in the center and the acies in front of it, extending from one end to the other. This is the arrangement which Holmes maintains would suit Caesar's text.

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7 Were it not for the north trench, the legions might have overlapped the camp, which would have suited both the six-legion hill-length and Holmes' unswerving insistence on the north as front. It was this point which originally determined Holmes to secede from Rutherford, for he was apparently convinced by Lehmann's measurements (Neue Jahrb. f. d. klass. Altertum, IV (1901) 506‑509 and Klio, VI (1906) 237‑248) of a legion front. However, it is abundantly clear from Lehmann's discussion that little satisfaction can be gained on this point, and the hill of Mauchamp is still suitable for either six or eight legions without a camp.

[decorative delimiter]

8 The orientation of the trenches is given in relation to that of the hill, not of the camp. Therefore it in no way concerns the correctness of the plan that the trenches protrude from the northwest and southeast corners of the camp. They are the north and south sides of the hill. Were they from the northeast and southwest, there would have been no such argument as has arisen on this point, for then the statement that the acies overlapped the camp would go unquestioned. The difficulty lies in the fact that both trenches are at the same, i.e. the east, end of the hill.

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9 When the Belgae by flank movement attempted to ford the Aisne, there is no mention of trenches in the account of thwarting it. Therefore it may be assumed (from the map) that the ford was considerably to the west of the hill. Yet when Caesar says they forded the Aisne quod esse post nostra castra demonstratum est, he suggests exactly the opposite (see note 4, above). This contradiction is explained only assuming that no trench existed to the west, or that where the Belgae forded the river was not post castra or anywhere near it. In either case Caesar is far from clear. In view of Holmes' statement (op. cit., 662, n. 1) that his former adherence to Rutherford involved the "unwarranted assumption that Caesar is misleading," it is worth pointing out that Caesar's description hardly deserves the close adherence which Holmes tries to give it. Such a sentence as Ubi nostros . . . possent has clearly run away with its writer. Rutherford is indeed charitable in calling it merely "involved."

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10 I cannot bring myself to believe that the problem has been materially altered by the views of Fr. Ebert (Bayr. Blätter f. d. Gymnas., LIV (1918), 30‑32), who maintains that Napoleon's plan is imaginatively based upon the excavations which do not actually correspond with the map. Ebert's investigations were carried on in 1916 by one who until then had never seen Napoleon's plan, and who was entirely controlled and limited by the exigencies of military trench digging. One may be permitted to doubt that such investigations carry the weight which would have accrued to them under more favourable circumstances. His main contention is that German trenches, cutting across what should have been the north, east, and south sides of Caesar's camp, showed no traces of the mixed brown and chalky earth which is the mark of filled-in entrenchments from antiquity. The west side he apparently could not investigate beyond noting that one may choose either of the two west gates as the one intended to be marked by the stone inscribed Porte d'Ouest left by Napoleon. Further, he claims to have found an ancient trench running parallel to the west side, one hundred meters to the east (not far enough away to be on the east side) and two hundred and fifty meters long, bisecting the northwest quarter of the camp as it appears on Napoleon's plan. Minor comments concerning the trenches are demonstrably wrong (e.g., that the castella must have been on the right and left wings of the front), and all measurements are subject to debate. The paper was avowedly written at the front, where consultation with Holmes (who is not even mentioned) or any other authority, except a minor work of Schlossman (Die Kämpfe Julius Cäsars an der Aisne: Leipzig [1916], was in particular. This is the more distressing because the site has been rendered useless for further investigation not only by the very trenches which Ebert's troops dug, but by a serious artillery duel there in 1917. Chaudardes has also suffered. Both sites were again on the front line in June, 1940.

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11 A. Gudeman's personal letter to Holmes (op. cit., 663) defining deiectus.

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12 E.g., the battle-field against the Helvetii near Annecy.º Here Bircher's revision of Stoffel-Napoleon (cf. Holmes, op. cit., 625‑7) requires the fighters to have crossed a small river three times in the course of the battle, though Caesar never mentions any river at all. One of the arguments in favor of Bircher's revision rests upon a highly subjective decision whether a certain hillside is too steep for a battle formation. In view of the arrangement of the Scotch described by Tacitus (Agric. 35), which was so advantageous to them, this is a dangerous point, especially when the slope may always have been used only for the first array, not for fighting at all.

Thayer's Note:

a And then maybe he did: I'm not familiar with the manuscript situation, but in many scripts the words planitiem and paludem are even more similar than they are in modern typefaces.

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Page updated: 26 Oct 18