Egypt in a single winter

Amr ibn al-As proposed to Umar that he take Egypt from the Byzantines with 4,000 men. Umar hesitated, then agreed with a sealed letter Amr was told to open only if he had crossed the frontier. Between the winter of 639 and the winter of 641 CE, Amr took Pelusium, Heliopolis, Babylon, and Alexandria.

Amr ibn al-As of the Banu Sahm was a late Meccan convert to Islam. He had been a merchant of the pre-Islamic aristocracy, a caravan leader who had traveled repeatedly to Byzantine Egypt and Byzantine Syria. He knew Egypt intimately, its cities, its geography, its garrison capacities, its bureaucratic weakness under Byzantine rule. He came to Umar ibn al-Khattab in Medina in 639 CE and proposed a campaign to take Egypt from the Byzantines.

Umar hesitated. The Muslim armies had already taken Syria and were pushing into Iraq and Persia. Egypt would be a fourth simultaneous campaign. The empire had been Muslim for less than a decade. Umar was cautious about overextension.

Amr made his case. Egypt was the richest granary of the Byzantine world. It fed Constantinople. Its Coptic Christian majority resented the Byzantine imposition of Chalcedonian Orthodoxy and would not fight for the Byzantines to the last man. Its garrisons were small and dispersed. Its Byzantine command was factional and divided. With 4,000 men, Amr said, he could take it.

Umar authorised the campaign but with a specific caution. He wrote Amr a sealed letter. He said: "Do not open this letter until you have crossed the frontier of Egypt. If it reaches you before you cross, turn back and forget the whole matter."

Amr set off from Palestine with 4,000 men in the winter of 639 CE. A courier caught up with him at al-Arish, just before the frontier. Amr saw the courier and knew what the letter contained, Umar had reconsidered and wanted him to turn back. Amr did not open the letter. He led his army forward at a fast pace and crossed the frontier of Egypt at Pelusium the same afternoon. He then opened the letter. It said, as he had guessed, that if the letter reached him before he crossed, he was to return.

Amr's clever technicality was that the letter had reached him at al-Arish, which was arguably not yet Egypt, but he had crossed into Egypt before opening it. He wrote to Umar acknowledging receipt and saying he had crossed before reading. Umar, receiving the news, was said to have smiled and said: let him proceed then, with the blessing of Allah. The classical Muslim historians take this exchange as one of the founding cases of the principle that a commander in the field has legitimate initiative that can override a caliph's caution when the field situation warrants.

The campaign followed a specific pattern. Amr targeted the strongest Byzantine positions first, took them, and used the political effect to secure the weaker positions by negotiation. Pelusium fell to a month-long siege in early 640. Amr then pushed inland, defeated a Byzantine field force at Heliopolis in July 640, and reached the great Byzantine fortress of Babylon of Egypt, a massive stronghold at the head of the Delta, near the site of modern Cairo, in September 640.

The siege of Babylon lasted six months, through the flooding of the Nile and into the spring. The Muslim army was reinforced by 4,000 additional troops sent by Umar. The Byzantine defenders were commanded by an aristocrat named Theodore. Amr negotiated privately with the Coptic patriarch Benjamin, who agreed that the Coptic Christian population would not resist. Babylon fell in April 641.

Amr moved on Alexandria the same summer. The Byzantine emperor Heraclius, who might have relieved the city, died in Constantinople in February 641 leaving a succession crisis. His son Constans II was too young to campaign. The Byzantine field forces in Egypt were leaderless.

Alexandria surrendered by treaty in September 641. The Byzantines negotiated a peaceful withdrawal. The Muslim army entered the city, one of the great cities of the ancient world, home of the library, the Pharos lighthouse, the intellectual capital of the eastern Mediterranean, without a fight.

Amr founded a new administrative capital at Fustat, "the tent," at the foot of the Byzantine fortress of Babylon. Fustat grew across centuries into al-Qahira (medieval Cairo) and then modern Cairo, the largest Arab city in the world today.

Amr governed Egypt for most of the following two decades. The Coptic Christian majority he had made peace with kept the peace. Egypt paid its jizya. It fed Medina. It fed Kufa. Amr's administration was famously light, he taxed at a rate lower than the Byzantines had, and Egyptian agricultural production increased under his rule.

He was the same Amr whom Umar publicly humiliated in Medina in the story of the Coptic boy at the horse race, the story of universal equal justice under law. Amr accepted the humiliation without complaint. The classical Muslim historians take this as evidence that the great generals of the early Islamic empire understood that their authority was delegated by the caliph and revocable, and that the caliph's judgment on justice was binding on the greatest of them.

What the story teaches

The conquest of Egypt is remembered by the classical Muslim historians for two lessons at once. First, that a small force with excellent intelligence and local knowledge can accomplish what a much larger force in ignorance cannot. Amr knew Egypt. He had traded there. He knew the Coptic-Byzantine tension. He knew who to negotiate with. He knew which fortress could be starved and which could not. Second, that the Islamic project of the early conquests was not simply extractive, it entered Egypt through a partnership with the Coptic Christian majority that Byzantine imperial religious policy had alienated. Amr's letter to Patriarch Benjamin promising freedom of religious practice to the Copts was the actual basis of Egypt's peaceful transition. The Islamic empire arrived in Egypt not by breaking a people but by liberating them from an imperial confessional imposition. The classical Muslim historians hold Amr up as the exemplar of the political intelligence the early caliphate could command: a merchant-general who had understood a country before he tried to conquer it.