Crowned Caesar Flavius Heraclius Augustus in 610. Latin was still the official language of the military and government. The Emperor faced invasions by Persians, Avars, Spanish Visigoths and Muslim Arabs. The Emperor personally commanded Roman troops in an invasion into the heart of Persia.  He crushed their Empire and forced Persian troops to evacuate the conquered Roman provinces of Egypt, Palestine, Syria and Mesopotamia.

Another 12,000 Muslim reinforcements were marching into Egypt to join with the 4,000 already there under Amr.. The smaller Arab force, commanded by a charismatic and tactically brilliant commander went behind enemy lines, and caused chaos all out of proportion to their size. 

The Roman commander Theodore had built up a considerable army of **perhaps 20,000 men** around the fortress of Babylon. 

Theodore had the opportunity to attack the smaller Arab army before the new army arrived. Instead out of fear? or excessive caution? Theodore remained inactive at Babylon.

The second army dispatched by Omar arrived at Heliopolis and began to lay siege to it. Amr retraced his route across the Nile River, and united his forces with those of the second army. They began to prepare for movement towards Alexandria – but scouts reported that Theodore and the Roman Army were finally on the move.

Why Theodore waited for the two smaller Arab armies to unite into one large army of 15,000 is not known. Perhaps Theodore was shamed by his officers for inaction.

Perhaps the morale of Theodore's troops was undermined by the reports of Arab victories against both the Persians and Romans in Syria and Mesopotamia. 

**Heliopolis** was a major city of ancient Egypt. It was the capital of the 13th or Heliopolite Nome of Lower Egypt and a major religious center.

The major surviving remnant of Heliopolis is the obelisk of the Temple of [Ra](https://en.wikipedia.org/wiki/Ra_(god))\-[Atum](https://en.wikipedia.org/wiki/Atum) erected by [Senusret I](https://en.wikipedia.org/wiki/Senusret_I) of [Dynasty XII](https://en.wikipedia.org/wiki/Dynasty_XII). It still stands in its original position, now within Al-Masalla in Al-Matariyyah, Cairo.

Heliopolis is the Latinized form of the Greek name *Hēlioúpolis* (Ἡλιούπολις), meaning **"City of the Sun"**.

**The Battle**

So in July, 640 Theodore decided to march out of Babylon and take on the now united Arab force. He advanced across the plain to attack Heliopolis.

We do not know much about the Roman troops - how much cavalry, infantry or local militia for example.

What we do know is Amr fought a brilliant battle at Heliopolis. 

When the Roman Army began approaching, Amr **divided his army into three separate units**, with one detachment under the command of a trusted commander, Kharija. Under the cover of darkness this unit marched abruptly east to nearby hills, where they effectively hid. This unit was to remain there until the Romans had begun the battle, at which point they were to fall on the Roman flank or rear, whichever was more vulnerable. The second detachment Amr ordered to the south, which would be the direction the Romans would flee if the battle went badly.

The two Arab flanking parties had moved in the dark and were not seen by the Romans.

The two main armies met in desperate hand hand-to-hand combat. Once the Roman forces initiated contact with Amr's forces and commenced an attack, the detachment of Kharija attacked the Theodore's rear, which was completely unexpected by the Romans.

**Theodore had not kept scouts out**, or, if he had, he ignored their warning of the approaching Arab horsemen.

This attack from the rear created utter chaos among the Roman ranks. As Theodore's troops attempted to flee to the south, they were attacked by the third detachment, which had been placed there for just such a purpose. This completed the final break-down and defeat of the Roman army, which fled in all directions.

Theodore survived, but with only a tiny fragment of his army, while the remainder was killed or captured. Many survivors retreated to the Fortress of Babylon.

**Aftermath**

In the battle's aftermath, most of southern and central Egypt fell to Amr's forces. **The defeat at Heliopolis was crucial, as it removed the last Roman force** standing between the Islamic invaders and the heart of Egypt. However, not only did the Battle of Heliopolis leave Egypt practically defenseless.

Bishop John of Nikiu said, "And thereupon the Moslem made their entry into Nakius, and took possession, and finding no soldiers (to offer resistance), **they proceeded to put to the sword all whom they found** in the streets and in the churches, men, women, and infants, and they showed mercy to none. And after they had captured (this) city, they marched against other localities and sacked them and put all they found to the sword. And they came also to the city of Sa, and there they found Esqutaws and his people in a vineyard, and the Moslem seized them and put them to the sword.

Sir Walter Scott was correct when he said **“the fate of Byzantine Africa was decided at the Battle of Heliopolis.”** 

The permanent loss of the Egypt left the Roman Empire without an irreplaceable source of food and money.

source: [https://byzantinemilitary.blogspot.com/2022/09/battle-for-africa-defeat-at-heliopolis.html](https://byzantinemilitary.blogspot.com/2022/09/battle-for-africa-defeat-at-heliopolis.html)

Collapse of the Roman Egypt and Africa. Battle of Heliopolis