Ancient Britain and the Invasions of Julius Caesar

by T. Rice Holmes

The reasons which point to the identification of the Portus Itius with Boulogne are, speaking generally, that Boulogne, and Boulogne only, satisfies all the requirements of Caesar’s narrative.

To begin with, the passage for sailing-vessels from Boulogne to the south-eastern part of Britain is, and always has been, in circumstances such as Caesar described, not only very convenient but by far the most convenient. This is the testimony of seafaring men, both English and French, who have practical experience of the winds and the currents in the Channel: it was admitted, or rather strenuously maintained, by Henry,[2868] who advocated the claims of Wissant; and any man who studies the Admiralty Chart—Dungeness to the Thames—the Channel Pilot, and the Atlas, published by the Admiralty, which is entitled Tidal Streams in the English and Irish Channels, may convince himself of its truth. Captain Pollet, the harbour-master of Calais and Boulogne, furnished information to Ernest de Saulcy, who was determined, by hook or by crook, to make out a plausible case in support of Wissant; but he avowed his own opinion that Caesar must have sailed from Boulogne.[2869] Captain Iron, the harbour-master of Dover, in conversation with me, has done the same.

Secondly, the whole of Caesar’s fleet could easily have assembled in the port of Boulogne; and they certainly could not have assembled in any other port, properly so-called, on the coast of the Morini,[2870] except the mouth of the Canche, which was several miles further from Britain than Boulogne, and was in no respect more convenient. Desjardins[2871] has shown that the estuary of the Liane was much broader and deeper in Caesar’s time than it was in the nineteenth century before the harbour was modernized, and that, as the headland which sheltered it has suffered greatly from erosion, it extended further seaward; and not only was it ample in extent, but it was the only port protected from every wind.[2872] No one has described its merits more eloquently than Henry, the advocate of Wissant; and no one was more competent to form an opinion. He describes Gesoriacum as ‘le havre le plus commode et le mieux situé de toute la Gaule-Belgique, pour le commerce, la construction et l’équipement des vaisseaux’.[2873] But, although it is certain that there would have been ample room in the Liane for Caesar’s 800 small vessels,[2874] Airy insists that it would have been impossible for them to clear the harbour in a single tide.[2875] Now Caesar does not say that they did clear the harbour in a single tide; nor is it necessary to assume that they did. Captain Iron has, however, assured me that Caesar’s fleet of shallow vessels could have cleared the harbour in a single tide even if the depth of the water then had been no greater than in 1877. In that year the depth at low tide was 1 metre 60, or more than 5 feet[2876]; and it may be regarded as certain that the draught of Caesar’s vessels in the second expedition was much less than five feet.[2877] The estuary of the Liane has been silted up so much since Caesar’s time that it would hardly be an exaggeration to say that its depth then was three times as much as in 1877;[2878] and it has been ascertained from the sinking of artesian wells at the cement works of M. Demarle at Capécure[2879] that at that place the ancient bed of the river is 19 metres below the level of spring tides.[2880]

Thirdly, the distance of Ambleteuse from Boulogne corresponds closely enough with Caesar’s estimate of the distance of the ulterior portus from the Portus Itius. This does not prove the identity of the Portus Itius with Boulogne: but, if it is not a fact, the Portus Itius was not Boulogne; and it is therefore necessary to examine the arguments of those who have denied it. ‘On measuring,’ says Airy,[2881] ‘upon the beautiful Admiralty Chart the distance between the centre of the entrance to Boulogne and the centre of the entrance to Ambleteuse, I find it to be not quite 4½ nautical miles, or 5½ Roman miles; instead of the 8 miles given by Caesar.’ This estimate is accurate; but it is also irrelevant; for Airy measures the distance by sea; and Caesar must have meant the distance by land. ‘It was quite immaterial,’ says Lewin,[2882] ‘what was the distance by sea, for the eighteen transports were windbound, and could not reach him; but, as he could not dispense with the vessels, he had to consider what portion of his force could be most conveniently despatched thither, and as the transports lay eight miles off, he thought it best, in order to save time, to send thither his cavalry ... by the nearest road from the port of Boulogne, through Wimille and Slacq to the church at Ambleteuse, the distance is twelve kilometres.’[2883] It is amusing to find that Airy, who lays so much stress upon the accuracy of Caesar’s (assumed) estimate of the distance by sea from the Portus Itius to the ulterior portus, maintains on the preceding page (Essays on the Invasion of Britain, &c., p. 27) that Caesar’s estimates of distances by sea were valueless.

Fourthly, Caesar’s narrative of the adventures of his cavalry transports is easily comprehensible on the hypothesis that the port from which he himself sailed was Boulogne, but on no other.[2884] As we have seen, the storm of the 30th of August, 55 B.C., which prevented them from making the Kentish coast near Caesar’s camp, drove some of them westward to a point on the south coast, and carried the rest back to the point whence they had started, namely, the ulterior portus. That port, if Caesar sailed from Boulogne, was Ambleteuse; and there is no difficulty in believing, nor has it ever been denied, that the wind, before which some of the ships ran from the neighbourhood of the South Foreland[2885] in the direction of Dungeness, would have carried the others, which were laid to, back to Ambleteuse.

Fifthly, Caesar, as we have seen, sailed from the Portus Itius with a south-westerly wind;[2886] and it is needless to tell any one who will consult the map that to sail with a south-westerly wind, especially with flat-bottomed vessels which made a great deal of lee-way, and on the easterly going stream, from Boulogne either to Sandwich, Deal, Walmer, Hythe, or Lympne, would have been easier than to sail from Wissant.

Sixthly, it is universally admitted that Boulogne, which Pliny[2887] calls the portus Morinorum Britannicus, was the permanent naval station of the Romans in the imperial epoch, and that it was the harbour from which they habitually sailed for the coast of Kent.[2888] An inscription preserved in the Boulogne museum[2889] proves that this station was established at least as early as the reign of Claudius, while Suetonius[2890] tells us that Claudius embarked at Gesoriacum for Britain. Indeed there is indirect evidence that the station existed in the time of Augustus; for the road which ran from Mediolanum (Milan) past Lugdunum (Lyons), Durocortorum (Reims), and Ambiani (Amiens), to Gesoriacum[2891] was constructed by Agrippa. It has been argued that, although Gesoriacum was the recognized harbour from the time of Augustus, the fact does not prove that it was the harbour from which Caesar sailed. But to those who admit that it has been proved that no other port existed which would have served Caesar’s purpose the fact will appear conclusive.[2892]

Seventhly, Desjardins[2893] has pointed out that Gallic ports were always either in the mouths of rivers or otherwise sheltered from storms. Such a port was Gesoriacum; and if Wissant was a Gallic harbour at all, it was a solitary exception to the rule.

Lastly, Rudolf Schneider[2894] lays great stress upon the fact that, according to Pomponius Mela,[2895] no harbour on the northern coast of Gaul was better known than Gesoriacum; and he reminds us that Pliny[2896] mentioned no other harbour in the country of the Morini. Unless, he argues, the Portus Itius was identical with Gesoriacum, Mela, Pliny, and the later writers must have forgotten its existence. Now nothing would be easier than to make a dialectical reply to this argument,—Is it not equally remarkable that none of these writers even hints that Gesoriacum was the Portus Itius? This was the reply which I made myself on another occasion. But the reply was sophistical. Schneider’s argument depends upon the assumption that the Portus Itius was one of the great harbours of Gaul; and considering that it could accommodate 800 vessels, this assumption is certainly reasonable. At all events it is impossible to suggest any other explanation of the fact that after Strabo no writer mentioned the Portus Itius for more than a thousand years, except this,—that the Portus Itius and Gesoriacum were one.

It would be waste of time to repeat the arguments, which have already been stated by implication in the section on Wissant, based upon the unique advantages that Boulogne possessed in being connected with the interior by river and road.[2897]