The Battle of Pelusium, an important city in the eastern extremes of Egypt's Nile Delta, 30 km to the southeast of the modern Port Said., was the first major battle between the Achaemenid Empire and ancient Egypt. This decisive battle transferred the throne of the Pharaohs to Cambyses II  of Persia, king of the Persians. It was fought near Pelusium in 525 BCE. The battle was preceded and followed by sieges at Gaza and Memphis.

Pelusium was an important city in the eastern extremes of Egypt's Nile Delta, 30 km to the southeast of the modern Port Said, becoming a Roman provincial capital and Metropolitan archbishopric, remaining a multiple Catholic titular see.