Charles Ellicott Commentary Isaiah 44:27

"that saith to the deep, Be dry, and I will dry up thy rivers;" — Isaiah 44:27 (ASV)

That says to the deep —i.e., to the Euphrates. The words find a literal fulfilment in the strategic operation by which Cyrus turned the river from its usual bed into the Sepharvaim channel, and thus enabled his soldiers to cross on foot (Herodotus 1.191). Symbolically, the words may mean simply the destruction of the power of Babylon, of which its river was the emblem. (Compare to Revelation 16:12.)