THE JULIAN CALENDAR AND THE CHRONOLOGY OF CAESAR’S INVASIONS OF BRITAIN
I. The chronology of Caesar’s first invasion of Britain is simple enough, so far as it can be ascertained, and requires no knowledge of the intricacies of the Roman calendar. I have shown in an earlier article that the disembarkation took place on the 26th or 27th of August, 55 B.C.[3550] After describing the storm which occurred on the night of August 30-31, and the consequent loss of many of his ships, Caesar goes on to say that the Britons endeavoured to protract the war by cutting off his supplies, and that he had corn brought in daily from the open country into his camp, and ordered the materials necessary for the repair of those ships which were only partially damaged to be fetched from the Continent. While the ships were being repaired an attack was made upon the 7th legion, which was engaged in cutting corn. This attack evidently took place several days after the 31st of August; for the field in which the legion was reaping was the only one accessible from the camp in which the corn had not been cut. The day on which the legion was attacked was followed by several days of stormy weather, during which all military operations were suspended. At the end of this time the Britons attacked the camp unsuccessfully, and on the same day sued for peace, which Caesar granted on condition of their giving hostages. Instead of waiting for the arrival of the hostages he ordered the British chiefs to send them over to the Continent, ‘because the equinox was at hand, and he did not think it wise to expose his unseaworthy ships to a voyage in stormy weather.’[3551] The equinox occurred on the 26th of September.[3552] Our data, then, are as follows:—the attack on the 7th legion occurred several days after the 31st of August; and Caesar returned to Gaul several days after the attack on the 7th legion, but before—probably several days before—the 26th of September.[3553] Let us say that he returned about the middle of the month. Napoleon, to whom indefiniteness was an abomination, fixed the 12th of September as the date.[3554]
II. If we were to believe certain writers of high reputation, we should be deterred from attempting to fix any dates for the second of Caesar’s expeditions; for our principal sources of information are dates mentioned by Cicero in his letters; and, as everybody knows, the Roman calendar, before Caesar’s reform, was often in disagreement with the Julian calendar. The writers of the article CALENDARIUM in Smith’s Dictionary of Greek and Roman Antiquities[3555] affirm that ‘it is very difficult or rather quite impossible to determine the actual dates which correspond to the nominal dates of any events before the Julian reform of the calendar’. But for the period comprised between the beginning of the year 696 (58 B.C.), just after Caesar became Governor of Gaul, and his reform of the calendar, which took effect in 709 (45 B.C.), this view is quite incorrect. Every date in Cicero’s correspondence which relates to the subject of this essay can be reduced, if not with absolute precision, at all events with a possible error of not more than one day, to its corresponding date in the Julian calendar. First of all, however, we must find out the nature of the reform which Caesar initiated, and understand the chronological disturbances which made reform necessary.
Every scholar knows that, after the period of the Decemvirate, the Roman year consisted of 355 days only, and that every other year an additional month, consisting alternately of 22 and 23 days, was, or rather ought to have been, intercalated after the 23rd of February. January, April, June, August, September, November, and December each contained 29 days; February 28; and March, May, July, and October 31. If I may remind the general reader of what he learned at school, the first day of every month was called the Kalends; the fifth day of January, February, April, June, August, September, November, and December was called the Nones; and the thirteenth day of each of those months was called the Ides. But in March, May, July, and October the Nones were on the seventh, and the Ides on the fifteenth day. In mentioning dates the Romans described any given day as occurring so many days before the Kalends, Nones, or Ides, as the case might be; and in so doing they adopted the inclusive method of reckoning. Thus the last day of December was called ‘the day before the Kalends of January’, pridie Kalendas Ianuarias, or shortly prid. Kal. Ian. But the 27th of December was called, not the third, but the fourth day before the Kalends of January, ante diem quartum Kalendas Ianuarias, or shortly a. d. IV Kal. Ian.
To return to the month which was or ought to have been intercalated every other year. As the ordinary year contained 355 days, and the solar year was believed to contain 365¼ days, it is obvious that to intercalate a month of 22 and 23 days alternately every other year was to make an excessive correction, the excess amounting to 4 days in every period of 4 years. Macrobius[3556] tells us that in order to remedy this error, 24 days were omitted from every twenty-fourth year. For various reasons, however, this regulation, if indeed it ever really took effect,[3557] was not always properly carried out; and accordingly in the year of the city 563, or 191 B.C., a reform was introduced, the college of pontiffs being authorized to intercalate or to omit intercalations at their discretion.[3558] But this innovation, as we learn from Cicero, Censorinus, and other writers, only made matters worse. Speaking of the pontiffs, Censorinus complains that ‘most of them, either from hatred or from favour, to cut short or to extend the tenure of office, or that a farmer of the public revenue might gain or lose more by the length of the year, by intercalating more or less at their pleasure, deliberately made worse what had been entrusted to them to set right’.[3559]
III. In 708 (46 B.C.), which is generally called ‘the year of confusion’, Caesar intercalated a certain number of days, in order to bring the calendar into harmony with the solar year before inaugurating the reformed calendar in 709. It is expressly stated by Asconius, whose testimony is unanimously accepted, that there was an intercalary month in 702;[3560] and it is admitted by all chronologists that there was no other intercalary month in the seven years between 700 and 708.[3561] There is no doubt that the Kalends of January, 709, corresponded either with the 1st or the 2nd of January, 45 B.C. It is clear, therefore, that when we have ascertained how many days were intercalated in 708, we shall be able, by reckoning backwards, to ascertain the correspondence of any given date in the summer of 700, the year of Caesar’s second expedition, with the Julian calendar,—with a possible error of one day only. This error will be removed if we can ascertain whether the Kalends of January, 709, corresponded with the 1st or the 2nd of January, 45 B.C.
All German scholars who have written upon Roman chronology are agreed that ‘the year of confusion’ contained 445 days, in other words, that 90 days, amounting to four ordinary intercalary months, were intercalated; and they hold that these 90 days were actually composed of three months, namely the Mercedonius, which, in the ordinary course, should in that year have been intercalated immediately after the 23rd of February, and two extraordinary months, amounting to 67 days, which were intercalated between the last day of November and the 1st of December. This view is supported in every detail by Censorinus,[3562] who wrote about 240 A.D. The principal dissentients are De La Nauze, Napoleon the Third and his collaborator, the famous astronomer, Le Verrier, who held that 67 days only were intercalated in 708, and Colonel Stoffel, who, in his Histoire de Jules César—Guerre civile, published in 1887, reaffirmed the same view, but who does not appear to have informed himself of what any of the Germans, except Ideler, had written on the subject. Moreover, the theory of Napoleon, Le Verrier, and Colonel Stoffel is frequently referred to by scholars in terms which imply that they regard the question as still open. The reason which Le Verrier[3563] gives is that in 700 Caesar re-embarked his troops for the return voyage from Britain to Gaul ‘because the equinox was at hand’ (quod aequinoctium suberat[3564]); that the equinox actually took place on the 26th of September of the Julian calendar; and that Caesar informed Cicero on the sixth day before the Kalends of October (which corresponded, on Le Verrier’s theory, with the 21st of September) that he was on the point of bringing back the army.[3565] He remarks that, on the theory of Ideler (who, like all other German scholars, held that 90 days were intercalated in 708), the sixth day before the Kalends of October, 700, would have corresponded with the 30th of August, 54 B.C.;[3566] and he argues that this theory must be wrong because Caesar would not have troubled himself about the approach of the equinox 27 days before it occurred. He also remarks that, although the view that 90 days were intercalated in 708 is supported by Suetonius[3567] and Censorinus,[3568] Dion Cassius[3569] affirmed that 67 days were intercalated, and that Dion expressly added that other writers had asserted that a greater number had been intercalated, but that his own statement was true; and he insists that Dion derived his information from authentic sources.[3570]
It will be shown presently that if Le Verrier was right in his interpretation of Dion’s words, Dion made a mistake. G. F. Unger[3571] holds that he misunderstood the authority from whom he borrowed his statement, and ‘who, like Suetonius, unquestionably regarded the month intercalated in February as an ordinary intercalary month’. Von Göler,[3572] on the other hand, holds that Dion was quite right; that he was referring, not to the ordinary intercalary month, but only to the two extraordinary months intercalated between November and December, which amounted to 67 days; and therefore that his statement tallies with that of Censorinus. Be this, however, as it may, it is absolutely certain that more than 67 days were intercalated in 708. For on the 16th of May, 705, Cicero wrote from Cumae, ‘At present the equinox is delaying us, which has been very stormy’ (Nunc quidem aequinoctium nos moratur, quod valde perturbatum erat[3573]). Now, on Le Verrier’s theory, the 16th of May, 705, corresponded with the 16th of April, 49 B.C. of the Julian calendar; but the equinox occurred on the 24th of March. In order to dispose of this difficulty, Le Verrier is obliged to have recourse to flagrant special pleading: ‘l’équinoxe,’ he says, ‘était passé depuis 21 jours,[3574] et les troubles atmosphériques pouvaient durer encore. Était-ce d’ailleurs autre chose qu’un prétexte pour Cicéron’?[3575] A very thin pretext, one would say,—a pretext which a man of Cicero’s intelligence was hardly likely to resort to.[3576]
But this is not the only proof of the unsoundness of Le Verrier’s theory. The argument which he bases upon Caesar’s words, quod aequinoctium suberat, shows that he completely misunderstands both Caesar’s narrative and the letter of Cicero to which he appeals. Cicero writes, ‘On the 24th of October I received letters from my brother Quintus and from Caesar, dated from the nearest coasts of Britain on the 25th[3577] of September ... they were on the point of bringing back the army’ (a Quinto fratre et a Caesare accept a. d. IX Kal. Nov. litteras, datas a litoribus Britanniae proximis a. d. VI Kal. Octobr. ... exercitum [e] Britannia reportabant[3578]). The letters to which Cicero refers were written, according to Napoleon and Le Verrier, on the 21st of September of the Julian calendar; and, they triumphantly remark, this tallies with Caesar’s statement, that he hurried on his departure from Britain ‘because the equinox was at hand’.[3579] But there is one fact which they overlook. Caesar had a large number of hostages and prisoners, and some of his ships had been lost. He was therefore obliged to transport the hostages, prisoners, and troops to Gaul in two successive trips. Only a few of the ships which made the first trip ever returned to Britain, almost all the rest having been driven back to Gaul by adverse winds. Caesar tells us that he waited for these ships ‘a considerable time (aliquamdiu) in vain’. Then, and not till then, he made the second trip, being obliged to crowd the soldiers into the few ships that he had, and not daring to wait any longer, ‘because the equinox was at hand.’[3580] The letters to which Cicero refers were evidently written before the first trip; for neither Caesar nor Quintus had written to Cicero for a long time;[3581] and they would naturally have dispatched their letters by one of the ships which made the first voyage. It is clear, therefore, that the letters in question were written, not on the 21st of September of the reformed calendar, but ‘a considerable time’ before that day. In fine, if Le Verrier and Napoleon were right, the letters would have been written not from Britain but from Gaul, and Cicero would have written not reportabant (‘they were on the point of bringing back’) but reportaverant (‘they had brought back’[3582]).