The Battle of Heliopolis was a decisive battle between Arab Muslim armies and Byzantine forces for the control of Egypt. The Arabs (Arabic: عرب ) are an ethnic group found throughout the Middle East and North Africa. ... A Muslim (Arabic: مسلم, Turkish: Müslüman, Persian and Urdu: مسلمان) is an adherent of Islam. ... Byzantine Empire (Greek: Βυζαντινή Αυτοκρατορία) is the term conventionally used since the 19th century to describe the Greek-speaking Roman Empire during the Middle Ages, centered at its capital in Constantinople. ...

The battle took place in mid-July 640, near the ancient city of Heliopolis, with Arab forces numbering 15,000 under the command of Amr ibn al-A'as, and the Byzantine forces numbering over 20,000 under Theodore, commander of all Byzantine forces in Egypt. Heliopolis (Greek Ἡλίου πόλις) was one of the most ancient cities of Egypt, and capital of the 13th Lower Egyptian nome. ... Amr ibn al-Ās (Arabic: عمرو بن العاص) (d. ...

With the Byzantine army approaching, Amr split his army into three sections, with one detachment under the command of a lieutenant, Kharija, heading east to near-by hills, and another detachment to the south. Once the Byzantine forces made contact with Amr's forces and attacked them, the detachment of Kharija fell on the Byzantine rear, causing turmoil among the Byzantine ranks. As Theodore's troops attempted to flee south-ward, they were attacked by the third detachment, causing a final break-down and defeat of the forces.

Though Theodore would manage to escaped with some survivors, most of southern and central Egypt fell to Amr's forces.

The next year and a half were spent on more maneuvers and skirmishes and seiegs, before the formal surrender of the capital, Alexandria, took place on Nov. 4, 641. For other uses, see Alexandria (disambiguation). ...