The first place to which he laid siege was Farwak, or Pelusium, situated on the shores of the Mediterranean, on the isthmus which separates that sea from the Arabian Gulf, and connects Egypt with Syria and Arabia.  It was therefore considered the key to Egypt.  A month’s siege put Amru in possession of the place; he then examined the surrounding country with more forethought than was generally manifested by the Moslem conquerors, and projected a canal across the isthmus, to connect the waters of the Red Sea and the Mediterranean.  His plan, however, was condemned by the Caliph as calculated to throw open Arabia to a maritime invasion of the Christians.

Amru now proceeded to Misrah, the Memphis of the ancients, and residence of the early Egyptian kings.  This city was at that time the strongest fortress in Egypt, except Alexandria, and still retained much of its ancient magnificence.  It stood on the western bank of the Nile, above the Delta, and a little east of the pyramids.  The citadel was of great strength and well garrisoned, and had recently been surrounded with a deep ditch, into which nails and spikes had been thrown, to impede assailants.

The Arab armies, rarely provided with the engines necessary for the attack of fortified places, generally beleaguered them, cut off all supplies, attacked all foraging parties that sallied forth, and thus destroyed the garrison in detail or starved it to a surrender.  This was the reason of the long duration of their sieges.  This of Misrah, or Memphis, lasted seven months, in the course of which the little army of Amru was much reduced by frequent skirmishings.  At the end of this time he received a reinforcement of four thousand men, sent to him at his urgent entreaties by the Caliph.  Still his force would have been insufficient for the capture of the place had he not been aided by the treachery of its governor, Mokawkas.

This man, an original Egyptian, or Copt, by birth, and of noble rank, was a profound hypocrite.  Like most of the Copts, he was of the Jacobite sect, who denied the double nature of Christ.  He had dissembled his sectarian creed, however, and deceived the emperor Heraclius by a show of loyalty, so as to be made prefect of his native province and governor of the city.  Most of the inhabitants of Memphis were Copts and Jacobite Christians, and held their Greek fellow-citizens, who were of the regular Catholic Church of Constantinople, in great antipathy.

Mokawkas, in the course of his administration, had collected, by taxes and tribute, an immense amount of treasure, which he had deposited in the citadel.  He saw that the power of the Emperor was coming to an end in this quarter, and thought the present a good opportunity to provide for his own fortune.  Carrying on a secret correspondence with the Moslem general, he agreed to betray the place into his hands on condition of receiving the treasure as a reward for his treason.  He accordingly, at an appointed time, removed the greater part of the garrison from the citadel to an island in the Nile.  The fortress was immediately assailed by Amru, at the head of his fresh troops, and was easily carried by assault, the Copts rendering no assistance.