in 602, the last byzantine-sasanian war began; it was the most devastating of the series of wars fought between the two empires. in 618, khosrau ii sent shahrbaraz to conquer egypt; one year later the sasanians managed to capture alexandria, the capital of byzantine egypt. after the fall of alexandria, the sasanians gradually extended their rule southwards along the nile. by 621, the province was securely in sasanian hands.