The Battle of Nikiou was a battle between Muslim troops lead by Amr ibn al-A'as and
Byzantine soldiers in Egypt on 646.
The victory wasa won at the Battle of Heliopolis in July of 640 where the capitulation of Alexandria was later followed in November of 641 when Arab troops taken over the Roman province of Egypt. The new Byzantine ruler Constans II was ready to take the land and lead a large fleet to carry troops to Alexandria and the troops were lead by Manuel and were able to take the city by surprise from the small Arab garrison at the end of 645. Historians say Amr may have been at Mecca and was recalled to take command of the Arab forces in Egypt.
The battle took place in a fortified town of Nikiou, very small and two-thirds of the way from Alexandria to Fustat, Arab forces numbered around 15,000 against smaller Byzantine forces. One of the champions were slain in single combat and the Arabs prevailed with Byzantine forces eventually retreating back to Alexandria.
The Byzantines closed the gates against Arabs who pursued them and the Arabs successfully conquered Alexandria when they stormed the city in the summer of that year. This was the last attempt by the Byzantine Empire to recapture Egypt for over 500 years due to Manuel's forces defeat, only Manuel I Komnenos sent an expedition there in the 12th century.