Cæsar had determined to make his exploratory voyage with two legions, the Seventh and the Tenth. He perhaps hoped that actual war would not be necessary to bring about the formal submission of the tribes on the coast, and he therefore did not take with him more than the 8,000 to 10,000 men, which were probably the actual muster of two legions, and a body of cavalry whose precise number is not stated. As fighting, however, might, after all, prove to be necessary, he took care that one of the legions which accompanied him should be the famous Tenth on whose courage and devotion he often relied, not in vain. To transport the legions he had collected about eighty cargo ships (_naves onerariæ_), many of which had been employed the year before in his naval campaign off the coast of Brittany. He had also a certain number of galleys (_naves longæ_) capable of being rowed much faster than the heavy transport ships could sail. On these latter his staff of officers, quæstors, legates and prefects were embarked, and no doubt the proconsul himself was their companion. The fleet set sail about midnight on August 26, B.C. 55, or on some day very near to that date. The port of embarkation was probably near to Cape Gris Nez and at the narrowest part of the channel, but almost every sentence of the following narrative has been the subject of an animated topographical discussion, and Cæsar himself mentions no names of places that can be certainly identified.[4] Whatever may have been the harbour from which the legions embarked it was not the same which had been appointed as a rendezvous for the cavalry. These latter were to be borne upon a little fleet of eighteen transports which were detained by a contrary wind at a port eight miles farther up the channel. As we shall see, their ill fortune in the matter of weather continued throughout the expedition, and their consequent inability to co-operate with the legions may have been the chief cause of the expedition’s failure.