Itius Portus

The main candidates have been Saint-Omer (Sithiu), Wissant and Boulogne (more usually called Gesoriacum and later Bononia), but a silted-up lagoon on the Flanders shore behind Calais now seems a most likely speculated area.

The same view was widely held about the second crossing, but T. Rice Holmes in an article in the Classical Review (May 1909) gave strong reasons for preferring Wissant, 4 miles (6.4 km) east of Gris Nez.

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[3] or opposed to brevissimus traiectus.

In 1944, French historian Albert Grenier, against the backdrop of the Allied invasion of Normandy, reanalysed Caesar's text against modern understanding of wind, weather, tides, and siltation in the English Channel.

[6] Boulogne is likewise presumed to have been the point of departure for the conquest of Britain of AD 43 under Aulus Plautius, although the only surviving account of the invasion, that of Cassius Dio, does not mention it.