Pompey made every effort in his power to aid Ptolemy's cause; but Lentulus, after long hesitation and delay, decided that it would not be safe for him to embark in it.

At length, however, Gabinius, the lieutenant who commanded in Syria, was induced to undertake the enterprise.

On certain promises which he received from Ptolemy, to be performed in case he succeeded, and with a certain encouragement, not very legal or regular, which Pompey gave him, in respect to the employment of the Roman troops under his command, he resolved to march to Egypt.

His route, of course, would lie along the shores of the Mediterranean Sea, and through the desert, to Pelusium, which has already been mentioned as the frontier town on this side of Egypt.

From Pelusium he was to march through the heart of the Delta to Alexandria, and, if successful in his invasion, overthrow the government of Berenice and Archelaus, and then, inviting Ptolemy to return, reinstate him on the throne.
In the prosecution of this dangerous enterprise, Gabinius relied strongly on the assistance of a very remarkable man, then his second in command, who afterward acted a very important part in the subsequent history of Cleopatra.