Deuteronomy 32:26

I said, I would scatter them into corners, I would make the remembrance of them to cease from among men:

This threat stands in the song Moses was commanded to compose from the events of Israel's history, recounting God's dealings with Israel and foreshadowing future events, including the final victory of the faithful when Christ comes again in power and glory. That song was meant to teach Israel's children and keep the history of God's dealings from being forgotten. It was given as a waymark of God's providential dealings, marking His goodness and mercy in His care and deliverance of His people.

It was to be taught by parents to their children and repeated in full when children asked about memorials kept in sight. It means God's dealings with His people should be often repeated and kept in mind, and it applies to the present as a pattern for recounting God's goodness, praising Him for His wonderful works, and coming before Him with praise and thanksgiving for joy and gladness. The threat itself answers Israel's rebellion and apostasy, worship of other gods, corruption, idolatry and unfaithfulness, departure from God and failure to honor His name, which provoked God's anger and brought judgment.

God declares His purpose to scatter His disobedient people into corners and make their remembrance cease from among men and nations, bringing sword and terror and calamity on those who persist in rebellion, which shows the severity of the coming judgment. Yet God restrains Himself from carrying that threat out fully, lest enemies boast strangely and exalt themselves by claiming their own strength defeated Israel and that the Lord had not acted. The surrounding passage explains defeat as the result of Israel being a nation void of counsel with no understanding, lacking wisdom to consider their latter end, so that any success of one chasing a thousand and two putting ten thousand to flight happens only because their Rock sold them and the Lord shut them up.

The warning was fulfilled when unfaithfulness brought captivity and the destruction of the Temple in which the people were scattered. The prophecy reveals God's love for His people and His abhorrence of sin, and its warning of calamity for continued apostasy made Josiah tremble for Judah's future as he recognized the nation's condition. Applied to the Civil War, the verse means God would not give the Northern army wholly into the hands of the Southern rebels to be utterly destroyed by them.

That restraint was not because the leaders trusted the God of Israel, for they trusted the prince of devils and spirits of devils instead, but to keep the adversaries from exalting themselves.