Umar and naval warfare
During the caliphate of Umar, Muawiyah had sought the permission of Umar to undertake naval warfare. Umar consulted 'Amr b Al 'Aas who was then the Governor of Egypt. 'Amr b Al 'Aas reported unfavorably in the following terms:
"O Commander of the Faithful, I have seen a numerous people going upon it overpowered by a few. When it is calm it tends the heart, and when it is in motion, it twists the brain. It weakens confidence and strengthens doubt. There is nothing there but sky and water. People at sea are like a worm in a log of wood. If their boat inclines they sink, and if they survive they are dazed."
Umar rejected the proposal of Muawiyah to undertake war on the sea in the following terms:
"I have heard that the Syrian Sea rises higher than the highest thing on earth, and it seeks Allah's permission day and night to spread over the earth and drown it. So how can I send forces over this terrible Kafir. By Him Who sent Muhammad with the truth, I shall never send any Muslim upon it."
Naval activities under Uthman
Uthman withdrew the restriction of naval warfare. He permitted Muawiyah to invade the island of Cypress. The island was captured by the Muslims. 'The success of the Cypress campaign set the stage for the undertaking of naval activities by the Government of Egypt as well. Abdullah b Sa'ad built a strong navy. He proved to be a good naval commander, and under him the Muslims won a number of naval victories.
The first naval clash between the Byzantine navy, and the Egyptian navy took place on the Egyptian coast in 651 C.E. In this naval action, the Byzantines who were the aggressors were repulsed with a heavy loss.