2. In his second expedition, Cæsar _embarked at the port Itius, which he had found to offer the most convenient passage for proceeding to Britain, distant from the continent about thirty Roman miles_. Now, even at the present day, it is from Boulogne that the passage is easiest to arrive in England, because the favourable winds are more frequent than at Wissant and Calais. As to _the distance of about thirty miles_ (forty-four kilometres), Cæsar gives it evidently as representing the distance from Britain to the _Portus Itius_: it is exactly the distance from Boulogne to Dover, whereas Wissant and Calais are farther from Dover, the one twenty, the other twenty-three Roman miles. 3. _To the north, at eight miles’ distance from the Portus Itius, existed another port, where the cavalry embarked_. Boulogne is the only port on this coast at eight miles from which, towards the north, we meet with another, that of Ambleteuse. The distance of eight miles is exact, not as a bird flies, but following the course of the hills. To the north of Wissant, on the contrary, there is only Sangatte or Calais. Now Sangatte is six Roman miles from Wissant, and Calais eleven. 4. _The eighteen ships of the upper port were prevented by contrary winds from rallying the fleet at the principal port_. We understand easily that these ships, detained at Ambleteuse by winds from the south-west or west-south-west, which prevail frequently in the Channel, were unable to rally the fleet at Boulogne. As to the two ships of burthen, which, at the return of the first expedition, could not make land in the same port as the fleet, but were dragged by the current more to the south, nothing is said in the “Commentaries” which would show that they entered a port; it is probable, indeed, that they were driven upon the shore. Nevertheless, it is not impossible that they may have landed in the little fishers’ ports of Hardelot and Camiers. (_See Plate_ 15.)