The first act of the war which caused Cæsar any misgivings was the pollution of his water supply by the enemy, and the consequent nervousness of his men. The Royal Area obtained its drinking water through subterranean channels communicating with the lake at the back of the city; and no sooner had Cæsar realised that these channels might be tampered with than he attempted to cut his way southwards, probably along the broad street[32] which led to the Gate of the Sun and to the Lake Harbour. Here, however, he met with a stubborn resistance, and the loss of life might have been very great had he persisted in his endeavour. Fortunately, however, the sinking of trial shafts within the besieged territory led to the discovery of an abundance of good water, the existence of which had not been suspected; and thus he was saved from the ignominy of being ousted from the city which he had entered in such solemn pomp, and of being forced to retire across the Mediterranean, his self-imposed task left uncompleted, and his ambitions for the future of Cleopatra unfulfilled.
Not long after this the welcome news was brought to him that the Thirty-seventh Legion had crossed from Asia Minor with food supplies, arms, and siege-instruments, and was anchored off the Egyptian coast, being for the moment unable to reach him owing to contrary winds. Cæsar at once sailed out to meet them, with his entire fleet, the ships being manned only by their Rhodian crews, all the troops having been left to hold the land defences. Effecting a junction with these reinforcements, he returned to the harbour, easily defeated the Egyptian vessels which had collected to the north of the Island of Pharos, and sailed triumphantly back to his moorings below the Palace.