Under Umar, 'Amr became the Governor of Palestine in 63X C.E. In 639 C.E. after the death of Ubaidullah b Jarah, 'Amr became the supreme commander of the armed forces in Syria. That provided him an opportunity to conquer Egypt. Umar was averse to the extension of Muslim dominions. When 'Amr b Al 'Aas pressed for the conquest of Egypt, Umar reluctantly gave his permission to try his luck in Egypt. 'Amr b Al 'Aas invaded Egypt with a small force in the closing months of 639 C.E. Egypt fell before the Muslim arms as if by a miracle.