For the town of ancient Thessaly, see Pelusium (Thessaly).
Pelusium lay between the seaboard and the marshes of the Nile Delta, about two and a half miles from the sea. The port was choked by sand as early as the first century BC, and the coastline has now advanced far beyond its ancient limits, so that the city, even in the third century AD, was at least four miles from the Mediterranean.
The principal product of the neighbouring lands was flax, and the linum Pelusiacum (Pliny's Natural History xix. 1. s. 3) was both abundant and of a very fine quality. Pelusium was also known for being an early producer of beer, known as the Pelusian drink. Pelusium stood as a border-fortress, a place of great strength, on the frontier, protecting Egypt as regards to Syria and the sea. Thus, from its position, it was directly exposed to attack by any invaders of Egypt; it was often besieged, and several important battles were fought around its walls.
Pelusium was the easternmost major city of Lower Egypt, situated upon the easternmost bank of the Nile, the Ostium Pelusiacum, to which it gave its name. Pliny the Elder gives its location in relation to the frontier of Arabia: "...At Ras Straki, 65 miles from Pelusium, is the frontier of Arabia. Then begins Idumaea, and Palestine at the point where the Serbonian Lake comes into view. This lake... is now an inconsiderate fen."
The Roman name "Pelusium" was derived from the Greek name, and that from a translation of the Egyptian one. It was variously known as Sena and Per-Amun  (Egyptian, Coptic: Ⲡⲉⲣⲉⲙⲟⲩⲛ Paramoun meaning House or Temple of the sun god Amun), Pelousion (Greek, Πηλούσιον), Sin (Chaldaic and Hebrew), Seyân (Aramaic), and Tell el-Farama (modern Egyptian Arabic). According to William Smith, it was the Sin of the Hebrew Bible (Ezekiel xxx. 15). Smith surmised that the word in its Egyptian and Greek forms (Peremoun or Peromi; πήλος) had the connotation of a 'city made of mud' (cf. omi, Coptic, "mud"). The anonymous author of the Aramaic Palestinian Targum has translated the word "Rameses" in the Pentateuch as meaning Pelusin (Pelusium). It is not certain whether or not the 10th-century rabbi and scholar, Saadia Gaon, agreed with that determination, although he possessed another tradition of later making, writing that Rameses mentioned in Numbers 33:3, and in Exodus 1:11 and 12:37, as also in Genesis 47:11, refers to the Egyptian town of ʻAin Shams. According to the 1st-century historian Josephus, Pelusium was situated on one of the mouths of the Nile. Modern-day historical geographers associate ʻAin Shams with the ancient city of Heliopolis.
The following are the most notable events in the history of Pelusium :
The khalifs who ruled Pelusium following the Crusades, however, generally neglected the harbors, and from that period Pelusium, which had long been on the decline, almost disappeared from history.
Of the six military roads formed or adopted by the Romans in Egypt, the following are mentioned in the Itinerarium of Antoninus as connected with Pelusium:
Pelusium became the seat of a Christian bishop at an early stage. Its bishop Dorotheus took part in the First Council of Nicaea in 325. In 335, Marcus was exiled because of his support for Athanasius of Alexandria. His replacement Pancratius, an exponent of Arianism, was at the Second Council of Sirmium in 351. Several of the succeeding known bishops of Pelusium were also considered heretical by the orthodox. As the capital of the Roman province of Augustamnica Prima, Pelusium was ecclesiastically the metropolitan see of the province.
In the nineteenth century, the diocese was nominally restored as a Metropolitan titular archbishopric Pelusium of the Romans.
It is vacant since decades, having had the following incumbents, of the highest rank with a single episcopal (lowest rank) exception :
Since its twentieth century establishment as Metropolitan titular archbishopric, Pelusium of the (Greek) Melkites has had the following incumbents, all of this highest rank :