Note 503 — Chapter X · (Year of Rome 702.) (Book VII. of the “Commentaries.”) REVOLT OF GAUL—CAPTURE OF VELLAUNODUNUM, GENABUM, AND NOVIODUNUM—SIEGES OF AVARICUM AND GERGOVIA—CAMPAIGN OF LABIENUS AGAINST THE PARISII—SIEGE OF ALESIA.

MM. de Saulcy and J. Quicherat have already demonstrated in a conclusive manner that Labienus must have followed the left bank of the Yonne, after leaving Sens, and that he crossed over to the right bank of the Seine at Melun. In fact, Labienus, on the right bank, found himself, as Cæsar says, threatened on one side by the Bellovaci, on the other by the army of Camulogenus (VII. 59). On the opposite bank, on the contrary, Labienus would not have been placed between the two, since he would have had Camulogenus in front, and, at a greater distance, the Bellovaci coming from the north.

“A very large river kept the legions separated from their reserve and their baggage.” This very great river cannot be the Marne, which Cæsar does not even mention in the whole course of this campaign: it was evidently the Seine, which Labienus has crossed once only, at Melodunum (Melun); by crossing over to the right bank, he was separated from his base of operations, which was at Sens. On the contrary hypothesis, no river would have separated Labienus from his line of retreat; unless we admit, with Dulaure and several others, the identity of Agedincum with Provius, which is no longer possible.

The Captain of the Staff Rouby has made investigations on the spot, which prove that from Sens the most ancient ways leading to Paris passed on the left bank of the Yonne and of the Seine. Moreover, the discoveries of M. Carré have made us acquainted with the exact direction followed by the Roman road after quitting Sens towards Paris; it was entirely on the left bank of the Yonne. If Cæsar’s lieutenant had followed the right bank of the Yonne, he would, the day after his departure, have been arrested by the course of the Seine, and would have fallen in with the Gaulish town of Condate, built in the very angle of the two streams, in the midst of perhaps impassable marshes. If only a few thousand Gauls had occupied the heights which played so important a part in the campaign of 1814, Labienus, compelled to seek for a place to cross higher up the stream, would have been diverted considerably from his aim.

It has been supposed wrongly that the Bièvre was the marsh where Labienus, in his march on the left bank of the Seine, had been arrested by the Gaulish army. Leaving out of consideration the fact that the Bièvre, which flows through a calcareous soil, can at no epoch have formed a marsh capable of arresting an army, how can we suppose that Labienus, if he had arrived at this stream, that is, close to Lutetia, would have retraced his steps as far back as Melun, to march from thence towards the oppidum of the Parisii by the right bank of the Seine, which would have obliged him to make a journey of twenty-four leagues? The manœuvre of Labienus can only be explained by his desire to turn the strong position of Camulogenus, and arrive at Paris before him. The text of the “Commentaries” says clearly that Labienus, stopped by the marsh which shelves towards the Seine, stole away by night, surprised the passage of the Seine at Melun, and marched upon Lutetia, where he arrived before Camulogenus. To allow of the success of this manœuvre, the marsh in question must necessarily not have been far from Melun. The Essonne alone fulfils that condition. The ground on the banks of this little river offers, even at present, by its nature, a very serious obstacle to an army. It is cut up by innumerable peat mosses; and it was behind this line of Essonne that, in 1814, the Emperor Napoleon I. established his army, whilst the enemy occupied Paris.