SIRBO´NIS LACUS(ἡ Σιρβωνίςor Σιρβωνίδος λίμνη, Hdt. 2.6; Diod. 1.30; Ptol. 4.5. § § 12, 20; Strab. i. pp. 50, 65, 17.760—763; Σίρβων, Steph. B. s. v.;Plin. Nat. 5.12. s. 14: Sebaket-Bardoil), was a vast tract of morass, the centre of which formed the Sirbonian lake, lying between the eastern angle of the Delta, the Isthmus of Suez, Mount Casius, and the Mediterranean sea. With the latter it was at one time connected by a natural channel (τὸ ἔκρεγμα), running through bars of quicksand and shingle (τὰ βάραθρα), which separated the sea from the morass. The limits of the Serbonian bog have, however, been much contracted in later ages by the elevation of the sea-borde and the drifting of the sands, and the lake is now of inconsiderable extent. The Sirbonian region is celebrated in history for having been the scene of at least the partial destruction of the Persian army in B.C. 350, when Darius Ochus was leading it, after the storming of Sidon, to Aegypt, in order to restore the authority of Persia in that kingdom. Diodorus (Diod. 1.30) has probably exaggerated the serious disaster into a total annihilation of the invading host, and Milton ( P. L. 2.293) has adopted the statement of Diodorus, when he speaks of that Serbonian bogBetwixt Damiata and Mount Casius oldWhere armies whole have sunk.
The same Persian army, however, afterwards took Pelusium, Bubastis, and other cities of the Delta. The base of the Deltaic triangle of Aegypt was reckoned by Herodotus (Hdt. 2.6) from the bay of Plinthine to the lake of Serbonis.
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