ITIUS PORTUS, the name given by Caesar to the chief harbour which he used when embarking for his second expedition to Britain in 54 B.C. (De bello Gallico, v. 2). It was certainly near the uplands round Cape Grisnez (Promuntorium Ilium), but the exact site has been violently disputed ever since the renaissance of learning. Many critics have assumed that Caesar used the same port for his first expedition, but the name does not appear at all in that connexion (B. G. iv. 21-23). This fact, coupled with other considerations, makes it probable that the two expeditions started from different places. It is generally agreed that the first embarked at Boulogne. The same view was widely held about the second, but T. Rice Holmes in an article in the Classical Review (May 1909) gave strong reasons for preferring Wissant, 4 m. east of Grisnez. The chief reason is that Caesar, having found he could not set sail from the small harbour of Boulogne with even 80 ships simultaneously, decided that he must take another point for the sailing of the " more than 800 " ships of the second expedition. Holmes argues that, allowing for change in the foreshore since Caesar's time, 800 specially built ships could have been hauled above the highest spring-tide level, and afterwards launched simultaneously at Wissant, which would therefore have been " commodissimus ". (v. 2) or opposed to " brevissimus traiectus " (iv. 21).
See T. R. Holmes in Classical Review (May 1909), in which he partially revises the conclusions at which he arrived in his Ancient Britain (1907), pp. 552-594; that the first expedition started from Boulogne is accepted, e.g. by H. Stuart Jones, in English Historical Review (1909), xxiv. 115; other authorities in Holmes's article.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)