Charles Ellicott Commentary Jeremiah 46:10

"For that day is [a day] of the Lord, Jehovah of hosts, a day of vengeance, that he may avenge him of his adversaries: and the sword shall devour and be satiate, and shall drink its fill of their blood; for the Lord, Jehovah of hosts, hath a sacrifice in the north country by the river Euphrates." — Jeremiah 46:10 (ASV)

This is the day of the Lord God of hosts. The prophet considers the outcome of all these great preparations, and sees that they will end in a disastrous overthrow, the righteous retribution for long years of cruelty and outrage. In doing so, he draws upon the language of earlier prophets (Isaiah 34:8; Zephaniah 1:7), and partly on that of Deuteronomy 32:42. There is to be a “great sacrifice,” and the army of Egypt is the destined victim; and the banks of the Euphrates (i.e., Carchemish) are to be as the altar.