Egypt was established as a Roman province and Octavian started appointing governors(praefectus Aegypti) of his choice after he defeated Cleopatra and Mark Anthony and the Roman Empire was established.
Egypt was established as a Roman province in consequence of the Battle of Actium, where Cleopatra as the last independent ruler of Egypt and her Roman ally Mark Antony were defeated by Octavian, the adopted heir of the assassinated Roman dictator Julius Caesar. Octavian then rose to supreme power with the title Augustus, ending the era of the Roman Republic and installing himself as princeps, the so-called "leading citizen" of Rome who in fact acted as an autocratic ruler. He thus established Egypt as an imperial province, to be governed by a prefect he appointed from men of the equestrian order. 
